DE102020113767B4 - Bicycle frame for an electric bicycle and method of manufacturing a bicycle frame - Google Patents

Abstract

Bicycle frame for an electric bicycle, which is assembled from a plurality of frame tubes (10, 11, 12, 13, 14), of which at least one frame tube (14) is designed as a frame profile assembly (20) with an outer profile body (30) and a battery carrier element ( 40) is formed, on which two spaced-apart battery holders (41) for receiving a battery (50) are fastened, the battery carrier element (40) has a profile carrier (42) which is integrally connected to the outer profile body (30) in one piece, thereby characterized in that the outer profile body (30) is a bent molded part.

Description

The invention relates to a bicycle frame for an electric bicycle according to the features in the preamble of claim 1. Furthermore, the invention is implemented in a manufacturing method for a bicycle frame.

An electric bicycle is generally understood to mean a bicycle with an electric motor which, alone or in support of the pedaling power of the cyclist, ensures propulsion of the bicycle. Such electric bicycles are called, for example, e-bikes, pedelecs or, if they are approved for higher permissible speeds, also s-pedelecs. In addition to an electrically operated drive motor, the electric bicycles necessarily have an energy store in the form of a rechargeable battery.

In early models, the accumulator was arranged in particular in the area of a luggage rack or placed on a frame tube of the bicycle frame such as the down tube. The DE 20 2018 103 882 U1 however, proposes integrating the accumulator completely into the down tube of the bicycle frame and covering it with a cover adapted to the contour of the down tube. The cover should be able to be removed and replaced in a simple manner without the use of tools, with the cover being securely locked in the fastened state and there being no risk of it falling out.

The DE 20 2018 004 175 U1 and suggests providing an opening in the down tube to prevent the accumulator from overheating, through which warm air can be drawn out of the inside of the frame tube.

In the DE 20 2017 003 771 U1 discloses a bicycle frame with a plurality of frame elements, of which at least one frame element is designed as an extruded profile with a plurality of chambers extending in its longitudinal direction. The extrusion profile should have an undercut profile section extending over part of the length, on which one or more fastening elements is/are held in a clamping manner and displaceable in the longitudinal direction.

Another prior art is the DE 10 2011 005 520 A1 with a bicycle frame, in particular for electric bicycles. The two-wheeler frame is assembled from a plurality of frame parts, of which at least one frame part has at least three profile elements which run next to one another at least in sections and are spaced apart from one another. For example, an accumulator is to be used in the installation space spanned by the profile elements. In the case of the frame part, at least three profile elements are combined to form an extrusion profile.

The DE 10 2017 200 829 A1 describes a vehicle frame that is particularly suitable for two-wheelers, the frame profile of which has at least one recess for accommodating a battery. In an inner concave area of the recess, the frame profile should be stiffened by means of a frame structure.

A bicycle frame with a frame tube manufactured by bending is the U.S. 5,255,932A refer to.

However, the known bicycle frames with batteries integrated into them are designed for a predetermined battery type with regard to the geometric dimensions of their outer profile body, usually a frame tube, so that it is necessary, for example, with new and more powerful batteries to redesign the entire bicycle frame . In addition, only accumulators that can be integrated into the frame tube due to their size can be used. However, under no circumstances should the wall thickness of the outer profile body be reduced to such an extent that an accumulator fits in but the strength of the bicycle frame is no longer given.

The object of the invention was therefore to provide a bicycle frame that can be adapted to different dimensions of accumulator types with little structural effort. A corresponding manufacturing process should also be developed.

The object is achieved according to the invention with the features of claim 1. It is also possible to accommodate several, in particular two, accumulators in associated frame profile assemblies. With two accumulators, two frame tubes are each provided as a frame profile assembly. The down tube and the top tube of the bicycle frame are particularly suitable for this. Dual operation is possible with two accumulators, which enables a significant increase in range and driving speed.

The frame profile assembly is constructed modularly from the outer profile body and the accumulator carrier element, with the profile carrier of the accumulator carrier element serving as an interface, which is or will be connected in one piece, integrally with the outer profile body. Under a one-piece, integral connection is a bottom den expected operating loads understood inseparable connection. This connection can be materially bonded and, in the case of a bicycle frame made of a steel or aluminum alloy, is in particular a welded connection.

The profile support can be designed, for example, as a square tube and, together with the outer profile body, is involved in the transmission of forces, as a result of which the bicycle frame is additionally stiffened. If a different accumulator is installed due to changed requirements, only the geometry of the outer profile body can be adjusted and the accumulator carrier element can continue to be used. This makes it possible to keep a large number of identical parts in stock, despite different bicycle frames and possibly differently dimensioned frame profile assemblies.

The accumulator holders are preferably fastened to the profile carrier. The accumulator can then be clamped between the two accumulator holders. The distance between the battery holders corresponds approximately to the length of the battery. Within certain limits, the distance between the two battery holders can be adapted to different lengths of the battery, so that batteries of different lengths can be installed in a frame profile assembly, which increases flexibility in production even further.

The outer profile body is advantageously penetrated in the axial direction by a slot which is delimited by opposite, free end sections of the outer profile body. The slot can be designed with a constant width over its axial length.

According to a particular embodiment, the profiled beam is inserted into the slot. For this purpose, the dimensioning of the profile carrier should be selected to complement the dimensioning of the slot. Favorably, the free end sections of the outer profile body rest on opposite sides of the profile body.

Expediently, the profile carrier terminates flush with the free end sections of the outer profile body on the outside. In this respect, only one side of the profile carrier is involved together with the outer profile body in a closed outer wall of the frame profile assembly. The result of this is that the profile carrier is no longer recognizable within the slot, which improves the visual appearance and reduces the susceptibility to corrosion due to the outwardly flat surface.

It has turned out to be particularly advantageous if the profile carrier is welded to the free end sections of the outer profile body. This is likely to be the case in particular with bicycle frames made from steel or aluminum alloys.

Expediently, the outer profile body is completely penetrated by the profile carrier in the axial length. This promotes the strength of the entire frame section assembly and the entire bicycle frame.

The outer profile body and the profile support can terminate together on a first and/or second, opposite end face. This makes it possible to fasten both the outer profile body and at least partially the profile carrier together on an adjacent frame tube or a frame adaptation plate and thus increase the fatigue strength of the bicycle frame.

An embodiment is particularly preferred in which two opposite sides of the outer profile body are formed as conically tapering side surfaces on the first and/or second end face. The tapered side surfaces reduce the width of the frame profile assembly to the diameter of the adjacent frame tube or a width of the frame adapter plate. This results in the advantage that the outer profile body for accommodating a larger accumulator can also be dimensioned larger than the diameter of the adjacent frame tube or possibly the width of the frame adaptation plate and still be in contact with it over the entire first and/or second end face, as a result of which a high level of strength is achieved .

The outer profile body is a bent molded part. This can be adapted particularly easily to different dimensions of the frame profile assembly. In addition, metal bent parts are particularly easy to weld.

The object is also achieved by a manufacturing method in which the accumulator carrier element has a profile carrier which is integrally connected to the outer profile body in one piece.

According to a further, special method step, the outer profile body and the profile carrier are first joined to form the frame profile assembly and then the frame profile assembly with the remaining frame tubes to form the bicycle frame. This makes it possible, independently of the production capacity of a frame welding machine, to produce a certain number of frame profile assemblies and these then to be installed in bicycle frames that are therefore structurally different, in particular for a men's or women's bike.

A contour of the outer profile body is cut out of a flat plate. The cutting out can be done in particular by means of laser cutting or water cutting.

Subsequently, separating joints for conically tapering side surfaces can be introduced into the contour.

Grooves corresponding to the course of bending lines are preferably introduced into the contour. As a result, a particularly precise groove course can be realized in a later bending process step.

The grooves are introduced in particular by means of water cutting.

The outer profile body is formed by bending the contour. A particularly dimensionally accurate shaping of the outer profile body is achieved by CNC bending of the contour along the previously introduced bending lines.

It is particularly favorable if, after bending, one or more two-shell shape-retaining tool(s) is/are applied to the outer profile body from the outside, the inner contour(s) of which corresponds to an outer contour of the outer profile body.

In addition, provision can be made to insert one or more shape-retaining core(s) into the outer profile body after bending, the outer contour(s) of which(s) corresponds/correspond in particular to an inner contour of the outer profile body.

The parting lines are expediently connected after the shape-retaining tool and/or the shape-retaining core has been put on. It has proven to be particularly advantageous if the joints are bridged by tack welding.

Advantageously, the shape-retaining tool and/or the shape-retaining core are removed and the parting lines are provided with a weld seam. Alternatively or additionally, the profile carrier can be welded to the outer profile body after the removal of the shape-retaining tool and/or the shape-retaining core.

In a final process step, the finished frame profile assembly is inserted into the bicycle frame and permanently connected to it.

• 1: einen Fahrradrahmen für ein Herrenrad mit eingebauter Rahmenprofilbaugruppe;
• 2: einen Fahrradrahmen für ein Damenrad mit eingebauter Rahmenprofilbaugruppe;
• 3: eine perspektivische Ansicht auf eine aus einer Platte herausgetrennte Kontur für einen Außenprofilkörper;
• 4: eine perspektivische Ansicht auf den aus der Kontur gebogenen Außenprofilkörper;
• 5: eine perspektivische Ansicht auf ein Formhaltewerkzeug und einen Formhaltekern;
• 6: eine perspektivische Ansicht auf ein Akkumulatorträgerelement mit angedeutetem Akkumulator;
• 7: eine perspektivische Ansicht auf einen mit dem Außenprofilkörper verbundenen Profilträger und
• 8: eine Abfolge erfindungsgemäßer Verfahrensschritte zum Herstellen eines Fahrradrahmens.

For better understanding, the invention is explained in more detail below with reference to eight figures. It show the

• 1 : a bicycle frame for a men's bike with built-in frame section assembly;
• 2 : a bicycle frame for a women's bike with built-in frame profile assembly;
• 3 1: a perspective view of a contour cut out of a plate for an outer profile body;
• 4 : a perspective view of the outer profile body bent out of the contour;
• 5 : a perspective view of a shape-retaining tool and a shape-retaining core;
• 6 1: a perspective view of an accumulator carrier element with an indicated accumulator;
• 7 : a perspective view of a profile support connected to the outer profile body and
• 8th : a sequence of method steps according to the invention for manufacturing a bicycle frame.

The 1 shows a perspective view of a bicycle frame for a men's bike, which is formed from a plurality of frame tubes 10 connected to one another at the ends. The frame tubes 10 include a top tube 11 which is inserted between a seat tube 12 and a head tube 13 . The head tube 13 accommodates a headset (not shown here), fixes a fork arranged underneath and connects the top tube 11 to a first end face 21 of a frame profile assembly 20, which forms a bottom tube 14 of the bicycle frame. An opposite, second end face 22 of the frame profile assembly 20 ends at a frame adaptation plate 15.

The top of the seat tube 12 accommodates a seat post, also not shown, and also ends at its lower end on the frame adaptation plate 15. Two chain stays 16 also run backwards from the frame adaptation plate 15 and go up in two at their distal end with respect to the frame adaptation plate 15 , In the direction of the top tube 11 running seat stays 17 over. The seat stays 17 are arranged on both sides of the seat tube 12 and act on the top tube 11 on opposite sides.

The frame adaptation plate 15 is designed in the form of a circular ring sector and, on its side facing away from the seat tube 12, the down tube 14 and the chain stays 16, takes a not shown bike gears up. With the help of the frame adaptation plate 15, which is always the same, the bicycle transmission can be adapted to different bicycle frames, for example to a bicycle frame for a men's bike 1 or for a women's bike accordingly 2 attach, increasing the number of identical parts and simplifying the logistics for parts to be kept available.

The frame profile assembly 20 replaces a lower tube 14 usually arranged at this position and is formed from the outer profile body 30 arranged on the outside and a battery carrier element 40 accommodated therein. On both end faces 21, 22 of the frame profile assembly 20, the outer profile body 30 tapers by means of conical side surfaces 33 arranged opposite one another in the direction of the head tube 13 and the frame adaptation plate 15 in such a way that the end faces 21, 22 are smaller than or equal to the outer diameter of the head tube 13 or a width of the Frame adaptation plate 15 are formed and can be connected to it over their entire contact surface. As a result, the section of the outer profile body 30 lying in between can be made larger and a battery 50 with larger dimensions can therefore be used.

In the representation of 1 is only a single battery holder 41 of a total of two battery holders 41 which is otherwise in 6 together with a battery 50 assembly of the battery carrier element 40 to recognize.

The frame profile assembly 20 is closed by means of a removable housing cover 23, which in the closed position accordingly 2 is locked with the outer profile body 30. For reasons of comfort, the housing cover 23 is arranged on the upper side of the outer profile body 30 in the bicycle frame provided for a men's bike, so that the accumulator 50 can be inserted into the frame profile assembly 20 from above and removed from it. Correspondingly for the bicycle frame intended for a women's bike 2 the upper tube 11 runs essentially parallel to the frame profile assembly 20 located underneath, which also takes over the function of the lower tube 14 here. A housing cover 23, which is also arranged on the upper side, would be difficult to remove because of the upper tube 11 arranged at a small distance above it, so that according to FIG 2 the frame profile assembly 20 was installed rotated about the longitudinal axis, the housing cover 23 is arranged on the underside and is freely accessible.

The 3 shows a contour 34 detached from a flat plate, in which according to the shape of the finished outer profile body 30 parting lines 35 for forming the conical side surfaces 33 and grooves 36 corresponding to later bending lines 37 for a subsequent bending of the contour 34 are introduced.

In the 4 the previously planar contour 34 was bent to form the outer profile body 30. A slot 31 that runs axially completely through the outer profile body 30 remains and is delimited in the circumferential direction by two end sections 32 of the outer profile body 30 that run parallel. The slot 31 occupies an in 6 illustrated profile carrier 42 of Akkumulatorträgerlelemente 40 on.

After the outer profile body 30 has been bent, the dimensional accuracy is checked by applying a shape-retaining tool 60 according to FIG 5 are checked, the inner contour 61 of an outer contour 38 ( 4 ) of the outer profile body 30 corresponds. In addition, a shape-retaining core 62 can be inserted into an interior 39 of the outer profile body 30 and then several axially offset shape-retaining tools 60 can be applied to the outer profile body 30 and the parting lines 35 can be connected to one another at least by tack welding. The shape-retaining tools 60 are constructed in two shells, can be applied to the outer profile body 30 from opposite sides and connected to form a single shape-retaining tool 60 via flange plates 60a. The shape-retaining tools 60 and shape-retaining cores 62 increase the dimensional accuracy during the welding and avoid a thermally induced distortion of the material due to the effect of heat during the welding.

After the mold-retaining tools 60 and the mold-retaining cores 62 have been removed, the accumulator carrier element 40 that has already been prepared is inserted into the outer profile body 30 and permanently connected thereto. The accumulator carrier element 40 comprises the rod-shaped profile carrier 42, which is designed as a square profile in the present exemplary embodiment, and the two accumulator holders 41 standing essentially orthogonally thereon, between which the accumulator 50 is clamped from opposite sides.

The 7 shows the profiled frame assembly 20 assembled from the outer profile body 30 and the accumulator carrier element 40. The profiled carrier 42 terminates flush in the radial direction outwards with the end sections 32 of the outer profile body 30 and is firmly connected to them by means of welding, as a result of which the flexural rigidity of the profiled frame assembly 20 is considerably improved . At the first and second end faces 21, 22, the profile carrier 42 and the outer profile body 30 end in a common plane according to the installation position relative to the head tube 13 or the frame adaptation plate 15, so that a joint connection of profile carrier 42 and outer profile body 30 with the head tube 13 or the frame adaptation plate 15 takes place at least in sections. The profile carrier 42 and the outer profile body 30 have the same axial length l.

The 8th illustrates process steps for producing the bicycle frame according to the invention. Firstly, a contour 34 is to be removed from a flat plate in order to produce an outer profile body 30 therefrom. In a further process step, parting lines 35 corresponding to the conical side surfaces 33 and grooves 36 corresponding to later bending lines 37 are introduced into the still planar contour 34 of the plate. A three-dimensional outer profile body 30 is then formed from the two-dimensional contour 34 by bending. The dimensional accuracy of the outer profile body 30 is checked and fixed by means of shape-retaining tools 60 and/or shape-retaining cores 62 . Subsequently, the parting lines are temporarily connected, in particular by means of tack welding, and the shape-retaining tool 60 and/or the shape-retaining cores 62 are then removed. In a final method step, the already completed frame profile assembly 20 is inserted into the bicycle frame and permanently attached to it at the intended position.

Reference List

10

frame tubes

11

top tube

12

seat tube

13

control tube

14

down tube

15

frame adaptation plate

16

chainstay

17

seatstay

20

frame profile assembly

21

first face

22

second face

23

housing cover

30

outer profile body

31

slot

32

End sections outer body profile

33

conical side faces

34

contour

35

parting line

36

grooves

37

bending line

38

Outer contour of outer profile body

39

Interior outer profile body

40

accumulator carrier element

41

battery holder

42

profile beam

50

accumulator

60

shape holding tool

60a

flange plate

61

Inner contour shape holding tool

62

shape-retaining core

I

axial length

Claims (13)

Bicycle frame for an electric bicycle, which is assembled from a plurality of frame tubes (10, 11, 12, 13, 14), of which at least one frame tube (14) is designed as a frame profile assembly (20) with an outer profile body (30) and a battery carrier element ( 40) is formed, on which two spaced-apart battery holders (41) for receiving a battery (50) are fastened, the battery carrier element (40) has a profile carrier (42) which is integrally connected to the outer profile body (30) in one piece, thereby characterized in that the outer profile body (30) is a bent molded part. bike frame claim 1 , characterized in that the accumulator holders (41) are attached to the profiled beam (42). bike frame claim 1 or 2 , characterized in that the outer profile body (30) is penetrated in the axial direction by a slot (31) which is delimited by opposite, free end sections (32) of the outer profile body (30). bike frame claim 3 , characterized in that the profiled beam (42) is inserted into the slot (31). bike frame claim 3 or 4 , characterized in that the profile carrier (42) with the free end sections (32) of the outer profile body (30) terminates flush to the outside. Bicycle frame according to one of the claims 3 until 5 , characterized in that the profile carrier (42) is welded to the free end sections (32) of the outer profile body (30). Bicycle frame according to one of the Claims 1 until 6 , characterized in that the outer profile body (30) and the profile carrier (42) terminate together on a first and/or second, opposite end face (21, 22). bike frame claim 7 , characterized in that the profile carrier (42) and the outer profile body (30) are connected to an adjacent frame tube (12, 13) on the first and/or second end face (21, 22). Method for manufacturing a bicycle frame for an electric bicycle, which is assembled from a plurality of frame tubes (10, 11, 12, 13, 14), of which at least one frame tube (10) is designed as a frame profile assembly (20) with an outer profile body (30) and an at least partially battery carrier element (40) arranged therein is formed, on which two battery holders (41) spaced apart from one another are fastened for receiving a battery (50), the battery carrier element (40) having a profile carrier (42) which is integral with the outer profile body (30), is integrally connected, characterized in that a contour (34) of the outer profile body (30) is cut out of a flat plate and the outer profile body (30) is formed by bending the contour (34). procedure after claim 9 , characterized in that first the outer profile body (30) and the profile carrier (42) to form the frame profile assembly (20) and then the frame profile assembly (20) with the remaining frame tubes (12, 13) are joined to form the bicycle frame. procedure after claim 10 , characterized in that in the contour (34) parting lines (35) for conically tapering side surfaces (33) are introduced. procedure after claim 9 until 11 , characterized in that in the contour (34) grooves (36) corresponding to a course of bending lines (37) are introduced. procedure after claim 12 , characterized in that the grooves (36) are introduced by means of water cutting.

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