DE102019205686B4 - Bicycle frame, method for manufacturing a bicycle frame and bicycle with such a bicycle frame - Google Patents

Abstract

Bicycle frame (2) with at least one frame tube (4) to which several stiffening elements (14a, 14b, 14c, 14d) are assigned, characterized in that: the stiffening elements (14a, 14b, 14c, 14d) are approximately T-shaped with a central part (16) and two support areas (18a, 18b), wherein the frame tube (4) has at least one integrally formed stiffening structure (20), and the stiffening structure (20) of the frame tube (4) has at least two stiffening ribs ( 22a, 22b), the stiffening ribs (22a, 22b) being formed internally on the underside of the frame tube (4) and extending in the direction of the longitudinal axis of the frame tube (4).

Description

The present invention relates to a bicycle frame according to the preamble of claim 1, a method for manufacturing a bicycle frame according to claim 14 and a bicycle according to the preamble of claim 15.

Electric bicycles, also known as eBikes, with different frame geometries and drive concepts are known from the prior art. For example, electric bicycles designed as step-through bikes with a down tube are known, with the down tube being designed for the removable accommodation of an energy store, a so-called battery pack.

A bicycle frame according to the preamble of claim 1 is from DE 10 2017 200 829 A1 known. Other bicycle frames are from the US 2018/0 065 705 A1 and from the DE 10 2017 115 998 B3 known. the U.S. 2006/0 130 307 A1 describes a method for manufacturing a bicycle handlebar

Due to the desired range of the eBike and the capacity required as a result, battery packs require a relatively large amount of installation space, so that a correspondingly large cutout must be provided in the down tube to accommodate the battery pack. Therefore, the rigidity of the frame tube must be ensured by means of multi-chamber designs of the down tube and the like, which are complex in terms of manufacturing technology.

In addition to the outlay in terms of production technology, the rigidity of these types of construction cannot be adjusted in a targeted manner, so that the frame as a whole has to be designed to be extremely rigid and is therefore not designed to be weight-optimized.

In addition to the outlay in terms of production technology, the rigidity of these types of construction cannot be adjusted in a targeted manner, so that the frame as a whole has to be designed to be extremely rigid and is therefore not designed to be weight-optimized.

Another disadvantage of these bicycle frames is that multi-chamber frame tubes produced in the extrusion process cannot be deformed, especially in the connection areas to the head tube and the motor mount of a bottom bracket motor, for example by means of a hydroforming process, and therefore cannot be attached in a form-fitting manner. A multi-part construction, which is complex in terms of manufacturing technology, is required.

The invention is therefore based on the object of providing a bicycle frame, a method for producing a bicycle frame and a bicycle, in particular a step-through bicycle, which bring electrically assisted mobility into line with the demands of sporty and lifestyle-oriented cyclists.

This object is achieved by a bicycle frame for an electric bicycle with the combination of features of claim 1, a method for producing a bicycle frame 14 and a bicycle according to the combination of features of claim 15.

A bicycle frame according to the invention has at least one frame tube, with a large number of stiffening elements being assigned to the frame tube. As a result, the rigidity of the frame tube can be specifically designed and adjusted without multi-chamber designs that are complex in terms of production technology, so that the frame is designed in a weight-optimized manner with a defined rigidity. It has proven particularly advantageous if the frame tube has no closed chambers.

The stiffening elements are approximately T-shaped with a central part and two bearing/support areas.

The down tube has at least one integrally formed stiffening structure. The stiffening structure of the down tube has at least two stiffening ribs/webs that extend axially and parallel to one another.

The stiffening ribs are formed internally on the underside of the down tube and extend in the direction of the longitudinal axis of the frame tube.

A further advantage of the bicycle frame according to the invention is that frame tubes produced in the extrusion process, preferably lower tubes, in particular in the connection areas to the head tube and the motor mount, can be deformed using a hydroforming process and can therefore be attached in a form-fitting manner. As a result, the bicycle frame can be made particularly slim and attractively filigree.

In a particularly preferred embodiment, the frame tube designed in this way is a down tube of the bicycle frame. The down tube is preferably designed in one piece and shaped according to the required geometry. A multi-part design of the down tube, which is complex in terms of manufacturing technology, is therefore not required. A maximum possible entry area is achieved overall, particularly in the case of a step-through design. The concept according to the invention therefore meets the high aesthetic and functional demands of a driver who emphasizes lifestyle and has sporting ambitions.

According to a preferred variant of the invention, the frame tube is an upper tube.

It has proven particularly advantageous if the stiffening elements extend as cross braces at an angle of approximately 90 degrees to the longitudinal axis of the frame tube, in particular the down tube.

According to an alternative embodiment of the invention, the stiffening elements extend as diagonal struts at an angle to the longitudinal axis of the frame tube, in particular the down tube. The diagonal struts can cross each other here, preferably in the middle, and form an X-arrangement. Multiple X arrays may be formed adjacently. A combination of transverse struts and diagonal struts is also advantageously possible. In particular, a crosswise arrangement of diagonal struts consisting of two diagonal struts can follow a transverse strut.

The stiffening elements are preferably arranged at a distance from one another in the frame part. The number and/or spacing of the stiffening elements are provided according to the required frame stiffness. As a result, the frame sections can have different levels of stiffness and also different degrees of stiffness.

In an exemplary embodiment of an electric bicycle according to the invention, the down tube has a cutout (recess) for the removable mounting of at least one energy store, in particular a battery pack, with the stiffening elements being provided in the area of the battery holder. As a result, the rigidity of the down tube is specifically optimized in the area of the cutout, without making the tube heavier as a whole.

According to an alternative exemplary embodiment of an electric bicycle according to the invention, the top tube has a cutout (recess) for the removable mounting of at least one energy store, in particular a battery pack, with the stiffening elements being provided in the area of the battery holder. As a result, the rigidity of the top tube is specifically optimized in the area of the cutout, without making the tube heavier as a whole.

In a further preferred variant of an electric bicycle, the lower tube and the upper tube each have a cutout (recess) for the removable mounting of at least one energy store, in particular a battery pack, with the stiffening elements being provided in the area of the battery holder. As a result, the rigidity of the down tube and the top tube is specifically optimized in the area of the respective cutouts, without making the tubes heavier as a whole.

The stiffening elements can also be used to attach the battery pack and/or electronic components (control unit, etc.).

In a preferred embodiment of the bicycle frame, the stiffening elements are arranged at regular intervals. Four stiffening elements are preferably provided.

The stiffening elements are preferably connected to the frame element by means of welding, soldering, screwing, gluing and/or riveting.

Webs that run in the middle allow the tube to be deformed at the end and/or at the beginning in order to be molded to the head tube and motor bracket in a form-fitting manner.

In a preferred embodiment of the bicycle frame, the stiffening ribs each have a fastening section and a flange area extending approximately at right angles to this, with the flange areas of adjacent stiffening ribs facing away from one another. This results overall in a hat profile-shaped stiffening structure.

The stiffening structure preferably extends from a control tube to the motor mount for a bottom bracket motor.

Alternatively, the stiffening structure extends from a head tube to the bottom bracket shell in a hub motor.

According to an alternative embodiment variant, at least one stiffening rib is formed on a side wall of the down tube.

According to the invention, stiffening ribs can be arranged on at least one side wall and the top wall or bottom wall.

When the battery is removed from the side, the stiffening ribs are preferably provided on the top wall, the bottom wall and on the one remaining side wall.

If the battery is removed downwards, the stiffening ribs are preferably provided on the top wall and the two side walls.

In the case of an alternative downward battery removal, the stiffening ribs are preferably provided on the upper wall.

The battery pack is preferably arranged adjacent to the motor mount and can therefore be particularly long with a correspondingly large capacity. In a variant with a bottom bracket drive (e.g. a motor-gear unit), the energy store can extend into an area of the bottom bracket drive mount. As a result, the lowest possible center of gravity of the bicycle with optimized handling is achieved with the greatest possible battery volume.

The battery pack is preferably adapted to the frame contour and complements the frame in an attractive manner when assembled.

In a preferred exemplary embodiment, the battery pack is removed upwards. This allows the user to easily insert the battery pack from above and lock it in the frame.

Alternatively, the battery pack can be removed from the side. The reinforcement struts and webs are then arranged accordingly laterally.

In a further preferred embodiment, the battery is removed downwards. The reinforcement struts and webs are arranged at the top in this variant.

It has proven to be particularly advantageous if the frame tube, for example the bottom tube or top tube, is designed as an extruded profile. Extrusion profiles can be produced with a high degree of automation at optimized costs.

The extrusion profile is preferably reshaped, at least in sections, by means of a hydroforming process.

The method according to the invention for producing a bicycle frame with at least one frame tube has the following steps: producing the frame tube by means of an extrusion process; Forming of the extruded frame tube by means of a hydroforming process and the introduction of stiffening elements into the extruded frame tube formed by means of a hydroforming ring. The frame tube produced in the extrusion process can still be shaped by means of the hydroforming process without stiffening elements inserted into it, in particular in the connection areas to the control tube and/or the motor mount. As a result, the frame tube, which is designed as a down tube according to a particularly preferred embodiment of the invention, can be designed in one piece and can be attached to the control tube and the motor mount in a form-fitting manner. The bicycle frame can be designed in an overall shapely manner and satisfies the highest strength requirements.

The construction according to the invention is particularly advantageous if the bicycle frame is designed as a step-through frame without a top tube. The advantages of a high-strength lower tube, which connects the head tube and motor mount, are particularly effective here, since the lower tube can be designed with defined rigidity and small cross sections for a maximum large and deep entry area due to the construction according to the invention. A visually appealing homogeneous design is made possible.

A step-through bicycle according to the invention has at least one down tube, with several stiffening elements being assigned to the down tube. As a result, the electric bicycle has an optimized frame cross-section with the best design and aesthetic properties while requiring minimal installation space.

The invention can be implemented universally with all types of bicycles and thus ultimately result in a city, touring or cross bike or other modern types of bicycle. Due to the compact, shapely design, it enables the construction of bikes that largely combine the advantages of a classic bike and an electric bike.

Further preferred embodiments are the subject matter of the dependent claims.

• 1 eine Seitenansicht eines Tiefeinsteigerfahrrads,
• 2 bis 5 jeweils eine räumliche Darstellung des Fahrradrahmens 2 aus 1,
• 6 einen Längsschnitt des Fahrradrahmens 2,
• 7 eine Draufsicht auf den Fahrradrahmen 2 und
• die 8 bis 10 jeweils eine Schnittdarstellung des Fahrradrahmens 2.

A preferred embodiment of the present invention is explained in more detail below with reference to the attached drawings. The drawings show in detail:

• 1 a side view of a step-through bike,
• 2 until 5 each a spatial representation of the bicycle frame 2 from 1 ,
• 6 a longitudinal section of the bicycle frame 2,
• 7 a plan view of the bicycle frame 2 and
• the 8th until 10 each a sectional view of the bicycle frame 2.

1 shows a schematic side view of a step-through bicycle 1 with a bicycle frame 2 having a frame tube designed as a down tube 4, which connects a head tube 6 to a motor mount 8 (so-called motor bracket). The motor mount 8 is designed to accommodate a non provided bottom bracket motor shown. The down tube has an arcuately curved connection area 10 towards the head tube.

A battery pack can be inserted into the bicycle frame 2 from above. For this purpose, the lower tube 4 has a cutout 12 .

Like the 2 until 5 it can be seen which spatial representations of the bicycle frame 2 from 1 show as well 6 , which shows a longitudinal section of the bicycle frame 2, four stiffening elements 14a, 14b, 14c, 14d are assigned to the down tube 4. As a result, the rigidity of the frame tube can be adjusted in a targeted manner without multi-chamber designs that are complex in terms of production technology, so that the frame is designed to be weight-optimized.

The lower tube 4 is produced by means of an extrusion process, it being deformed in particular in the connection area 10 to the control tube 6 by means of a hydroforming process. The four stiffening elements 14a, 14b, 14c, 14d are then inserted into the down tube 4 and welded to it. The frame tube produced in the extrusion process can still be deformed without stiffening elements inserted into it. As a result, the control tube 6 can be attached to the down tube 4 in a form-fitting manner. The bicycle frame is elegantly designed and meets the highest strength requirements.

This design is particularly advantageous if the bicycle frame 2 is designed as a step-through frame without a top tube, as shown. The advantages of a high-strength lower tube 4, which connects the head tube 6 and motor mount 8, are particularly effective since the lower tube 4 can be designed with a defined rigidity and small cross-sections for a maximally large and deep entry area due to the construction according to the invention. A visually appealing homogeneous design is made possible.

How in particular 7 can be seen, which shows a plan view of the bicycle frame 2, the stiffening elements 14a, 14b, 14c, 14d extend as cross braces at an angle of 90 degrees to the longitudinal axis of the down tube 4 and are evenly spaced. The number and spacing of the stiffening elements 14a, 14b, 14c, 14d are provided according to the required frame stiffness.

According to 8th , which shows a sectional view of the bicycle frame 2 in the area of the stiffening element 14d, as well as further sectional views of the bicycle frame 2 according to FIG 9 and 10 , the stiffening elements 14a, 14b, 14c, 14d are each T-shaped with a central part 16 and two bearing sections 18a, 18b pointing away from one another. The down tube 4 has an integrally formed stiffening structure 20 . The stiffening structure 20 extends from the control tube 6 to the motor mount 8 and has two stiffening ribs 22a, 22b which extend axially and parallel to one another. The two stiffening ribs 22a, 22b are formed on the inside on the underside of the down tube 4 and in the middle. The adjacent, spaced-apart stiffening ribs 22a, 22b extend in the direction of the longitudinal axis of the down tube 4.

The stiffening ribs 22a, 22b each have a fastening section 24 and a flange area 26 extending approximately at right angles to this, the flange areas 26 of adjacent stiffening ribs 22a, 22b facing away from one another. The stiffening ribs 22a, 22b are approximately L-shaped. This results overall in a hat profile-shaped stiffening structure 20.

The T-shaped stiffening elements 14a, 14b, 14c, 14d are inserted flush with the central part 16 between the stiffening ribs 22a, 22b in such a way that they rest on the left and right of the fastening sections 24 of the stiffening ribs 22a, 22b. The two support sections 18a, 18b of the stiffening elements 14a, 14b, 14c, 14d here rest on the left and right on the flange regions 26 of the stiffening ribs 22a, 22b.

A bicycle frame 2 with at least one frame tube 4 is disclosed, with the frame tube 4 being assigned a plurality of stiffening elements 14a, 14b, 14c, 14d. Also disclosed is a method for producing a bicycle frame 2 with at least one frame tube 4, preferably a down tube, with the steps: producing the frame tube 4 by means of an extrusion process; Reshaping of the extruded frame tube 4 by means of a hydroforming process and subsequent introduction of stiffening elements 14a, 14b, 14c, 14d. Also disclosed is a step-through bicycle 1 with at least one frame tube 4, preferably a down tube, with the frame tube 4 being assigned a plurality of stiffening elements 14a, 14b, 14c, 14d.

reference list

1

step-through bike

2

bike frame

4

down tube

6

control tube

8th

engine mount

10

connection area

12

cutout

14a

stiffening element

14b

stiffening element

14c

stiffening element

14d

stiffening element

16

center part

18a

support section

18b

support section

20

stiffening structure

22a

stiffening rib

22b

stiffening rib

24

attachment section

26

flange area

Claims (15)

Bicycle frame (2) with at least one frame tube (4) to which several stiffening elements (14a, 14b, 14c, 14d) are assigned, characterized in that: the stiffening elements (14a, 14b, 14c, 14d) are approximately T-shaped with a central part (16) and two support areas (18a, 18b), the frame tube (4) having at least one integrally formed stiffening structure (20), and the stiffening structure (20) of the frame tube (4) having at least two stiffening ribs extending axially and parallel to one another (22a, 22b), the stiffening ribs (22a, 22b) being formed on the inside on the underside of the frame tube (4) and extending in the direction of the longitudinal axis of the frame tube (4). bike frame claim 1 , wherein the frame tube (4) is a down tube. bike frame claim 1 , wherein the frame tube (4) is an upper tube. Bicycle frame according to one of the preceding claims, wherein the stiffening elements (14a, 14b, 14c, 14d) extend as transverse struts at an angle of approximately 90 degrees to the longitudinal axis of the frame tube (4). Bicycle frame according to one of the preceding claims, wherein the stiffening elements (14a, 14b, 14c, 14d) are arranged at a distance from one another within the frame tube (4). bike frame claim 5 , wherein the stiffening elements (14a, 14b, 14c, 14d) are arranged at regular intervals. Bicycle frame according to one of the preceding claims, wherein the frame tube (4), preferably the down tube, has at least one cutout (12) for the removable mounting of an energy store, in particular a battery pack, the stiffening elements (14a, 14b, 14c, 14d) in the cutout area of the frame tube (4) are provided. Bicycle frame according to one of the preceding claims, wherein the stiffening elements (14a, 14b, 14c, 14d) are connected in the frame element (4) by means of welding, soldering, gluing, screws and/or rivets. Bicycle frame according to one of the preceding claims, wherein the stiffening ribs (22a, 22b) each have a fastening section (24) and a flange region (26) extending approximately at right angles to this, and the flange regions (26) of adjacent stiffening ribs (22a, 22b) face away from one another . bike frame after claim 9 , wherein the stiffening structure (20) extends from a control tube (6) to a motor mount (8) for a bottom bracket motor. Bicycle frame according to any one of the preceding claims except according to claim 3 , wherein the bicycle frame (2) is designed as a step-through frame without a top tube. Bicycle frame according to one of the preceding claims, in which the frame tube (4), preferably the down tube, is designed as an extruded profile. bike frame claim 12 , wherein the extrusion profile is formed by means of a hydroforming process. Method for manufacturing a bicycle frame (2) according to any one of the preceding claims, the method comprising the following steps: - Manufacture of the frame tube (4) by means of an extrusion process; - Reshaping of the extruded frame tube (4) by means of a hydroforming process and - Introduction of stiffening elements (14a, 14b, 14c, 14d) in the frame tube (4). Bicycle, in particular step-through bicycle (1), with a bicycle frame (2) according to one of the preceding Claims 1 until 14 .

Images