DE102021104718A1 - Children's balance bike frames and children's bicycle frames - Google Patents

Abstract

A children's bicycle frame (110) comprises a head tube (118) for accommodating a front wheel fork and a handlebar, a seat tube (115) for accommodating a seat post and a bottom bracket mount (112). Seat stays (116) extend from the seat tube (115) to a rear wheel mount (114) and chain stays (113) from the bottom bracket mount (112) to the rear wheel mount (114). The children's bicycle frame (110) is designed as a one-piece plastic injection molded part, with at least a section is hollow, which is divided into: - a main section (111.1), which runs from the head tube (118) to a front branching point (111.2), - an upper tube section (111.3), which extends from the front branching point (111.2 ) up to an upper apex (111.4), on which the seat tube (115) is arranged;- a down tube section (111.5), which as a continuation of the main section (111.1) extends from the front branching point (111.2) to the bottom bracket mount (112 ) extends. In a child balance bike frame, the main tube descends in a main section from the head tube to a lower apex in front of the seat tube and rises from there in a secondary section up to an upper vertex through which the seat tube is guided. The rear wheel struts drop down from the top apex to the rear wheel mount.

Description

The invention relates to a children's balance bike frame with the features of the preamble of claim 1 and a children's balance bike frame with the features of the preamble of claim 7.

A classic bicycle frame construction is referred to as a diamond frame. This forms a spatial framework that has two triangles in the side view. A front triangle is formed by a down tube and a top tube, which emanate from a head tube, in which the front wheel fork and the handlebars are accommodated, and which connect to a seat tube, in which the seat post is guided. The seat tube ends at a bottom bracket mount. A second triangle is formed on each side of the rear wheel by the seat tube, a chainstay and a seatstay, with the chainstay extending from the bottom bracket to a rear wheel well and the seatstay extending from an upper portion of the seat tube to the rear wheel well. The frame thus comprises seven struts and six nodes. This frame shape is stable and has proven itself.

If a lower entry is desired, the statically balanced frame construction has to be abandoned because the top tube as a direct connection between the head tube and seat tube has to be omitted. On women's bikes, the top tube is often routed parallel to the down tube, which can only be seen as a compromise between strength and comfort. The barrier to entry is still high.

Step-throughs for seniors are also known, for example from DE 10 2006 007 862 A1 , where there is no longer a division into top and bottom tube, but only one large main tube. It has a constant curvature in the area in front of the bottom bracket and requires a well-developed knot there.

Balance bikes for toddlers and bikes for children have a significantly lower weight load than bikes for adults. Therefore, the top tube is usually completely omitted with this type of product. Children's balance bikes for small children up to around 3 years of age, which usually have 12-inch tires, are designed for a maximum load of 20 kg. Children's bicycles for slightly older children have tires with a diameter of 14 inches or 16 inches.

Children's balance bikes often have a children's balance bike frame that extends in an almost linear path from the head tube to the rear wheel mount, with the children's balance bike frame branching into two rear wheel stays in the area of the saddle tube. Such a children's balance bike is out EP 2 964 514 B1 known.

One disadvantage is that the entry height in front of the saddle is still relatively high because the main tube of the balance bike frame is still about three quarters of the way up there - in relation to the total height difference between the head tube and the rear wheel mount. In addition, the force curve is unfavorable because the weight of the child acts almost perpendicularly on the child's balance bike frame via the seat post, and at the point where the fork of the rear wheel stays attaches, which is statically unfavorable and prevents lightweight construction.

The object of the present invention is therefore to specify a children's balance bike frame that can be produced inexpensively and has a low mass.

This object is achieved by a children's balance bike frame with the features of claim 1.

The children's balance bike frame according to the invention is optimized in terms of resilience and is designed as a light, hollow plastic injection molded part made of thermoplastic material. The cross section of the balance bike frame has at least one cavity, at least in the area referred to as the main tube, between the head tube and the seat tube, so it is tubular at least there. This leads to a reduction in mass. The use of a thermoplastic material to manufacture the children's balance bike frame further reduces the mass and enables sorted recycling. Embedded metal parts, especially for the head tube and seat tube, can be easily separated for recycling.

Special advantages in terms of resource conservation and environmental protection result from the fact that any type of surface treatment can be dispensed with. While conventional running and bicycle frames made of metal have to be greased during production and then degreased again with solvents and then painted in several layers, the children's balance bike frame according to the invention can be produced directly and ready for use in the desired color by mixing in a masterbatch provided with dyes . In addition, a high-gloss surface or a surface with an individual surface structure can be obtained, depending on requirements. Inscriptions and decorations on the children's balance bike frame can be three-dimensional and therefore have a different perceptibility than glued-on surface motifs.

According to the invention, the main tube is designed as a hollow profile over the entire course between the head tube and the upper apex on the seat tube, which is produced by a fluid injection process. The production in the form of a plastic injection molded part made of a fiber-reinforced thermoplastic material in connection with the optimized children's balance bike frame shape has the advantage that the fibers flow along the walls of the mold during production and that the finished part is aligned in the longitudinal extension of the wall, so that with a low wall thickness a sufficiently high strength can be achieved. The flowing course of the children's balance bike frame with constant transitions is mechanically advantageous. In the children's balance bike frame according to the invention, sharp-edged transitions, acute angles and other areas with a high notch effect, which lead to stress concentrations, are avoided. Rather, all transitions are generously rounded and run steadily. The fact that the main tube from the head tube initially slopes down further than intended for the saddle position, and then rises again from a front, lower apex to an upper apex, allows a deeper entry in front of the saddle.

What is important is the formation of a seat tube, which is passed through the upper apex of the children's balance bike frame, without itself forming a load-bearing part in the linear progression between a main tube and the rear wheel struts. As a result, the two essential angles between the sections of the children's balance bike frame can be increased because there is no dependence on the angle of inclination of the seat tube. With the passage of the seat tube through the upper apex, the weight force is introduced at a particularly strong point.

Because the seat tube is embedded in at least one rib below the main tube, the area below the upper apex, and thus between the fork attachment of the rear wheel stays and the front apex, is stiffened.

A further object of the present invention is to specify a children's bicycle frame which can also be produced inexpensively and has a low mass.

This problem is solved by a children's bicycle frame with the features of claim 7 .

In the case of the children's bicycle frame, the concept of the children's balance bike frame described above is continued and supplemented by a bottom bracket for a pedal drive. The course of the main tube of the children's balance bike frame is almost identical in its upper area to that of the children's balance bike. With the children's bicycle frame, too, the weight of the child is introduced into the children's balance bike frame via a seat tube at the upper apex. The children's bicycle frame is also designed as a thermoplastic plastic injection molded part, which is designed in one piece at least in the area of the main tube and as a hollow profile.

The support below the upper apex differs from the impeller. Since a bottom bracket is required for a children's bicycle and since additional tensile forces act on the children's balance bike frame via the drive chain or the drive belt, the main tube descending from the head tube is extended via a front branching point to a bottom bracket mount. Two chainstays extend from there to the rear wheel mount.

In a preferred embodiment of the children's bicycle frame according to the invention, the stiffening of the main tube at the upper apex is effected via the seat tube, which is supported on or connected to the bottom bracket. The bottom bracket and seat tube thus form a T-shaped configuration, which consists in particular of metallic materials. The seat tube that is passed through a top tube section of the children's bicycle frame has a significantly smaller cross section than the children's balance bike frame itself. On the one hand, this does not weaken the plastic frame too much in the area of the upper passage of the seat tube. On the other hand, there are no accumulations of material for ribs and other structures in the plastic, because the stiffening between an upper tube section and a lower tube section takes place solely by means of the seat tube and is sufficient. The area of the children's bicycle frame between the top tube section and the bottom bracket mount remains open and is only traversed by the seat tube.

The support of the seat tube directly on the bottom bracket is advantageous because in this way the forces introduced via the narrow seat tube are distributed over a large area to the lower shell of the bottom bracket and the plastic frame is not subjected to point loads at this point.

In the case of children's bicycle frames, it is particularly advantageous if the chain stays and the seat stays do not unite at the rear wheel mount, but are connected to one another there via detachable hub elements. This makes it possible, on the one hand, to be able to attach an endless drive belt or a chain at any time without having to open it. On the other hand, with this design, the respective ends of the two struts can form outlet openings in order to avoid this during production discharge water from the children's bicycle frame using fluid injection technology.

One of the advantages of designing the children's bicycle or impeller frame according to the invention as a thermoplastic component is the high degree of dimensional accuracy, particularly with regard to the angle tolerances. As a result, an angular deviation in the relevant angular relationships, namely between the seatstays and the top tube section and a main section and the top tube section, is very small. Here, the tolerance is only about 1°, while in the case of frames conventionally made of aluminum profiles or steel tubes, an angular tolerance of only 3° to 5° can be achieved with reasonable effort during manufacture.

• 1 ein Kinderlaufrad in seitlicher Ansicht;
• 2A, 2B jeweils einen Kinderlaufradrahmen in seitlicher Ansicht;
• 3 einen Kinderlaufradrahmen in perspektivischer Ansicht von schräg unten;
• 4 ein Kinderfahrrad in seitlicher Ansicht;
• 5A, 5B jeweils einen Kinderfahrradrahmen in seitlicher Ansicht;
• 6 den Kinderfahrradrahmen in perspektivischer Ansicht von schräg oben;
• 7 den Kinderfahrradrahmen in perspektivischer Ansicht von schräg unten;

The invention is explained in more detail below with reference to the exemplary embodiments illustrated in the drawings. The figures show in detail:

• 1 a children's balance bike in a side view;
• 2A , 2 B each a children's impeller frame in a side view;
• 3 a children's impeller frame in a perspective view obliquely from below;
• 4 a children's bicycle in side view;
• 5A , 5B each a children's bicycle frame in a side view;
• 6 the children's bicycle frame in a perspective view diagonally from above;
• 7 the children's bicycle frame in a perspective view diagonally from below;

1 shows a children's balance bike 200 in a side view, which has two wheels 230, 240 of different sizes in this exemplary embodiment. The front wheel 230 is inserted into a front wheel fork 220 at a front wheel mount 221 . This is connected to a link 224 . The unit consisting of the front wheel fork 220 and the handlebar 224 is guided through a head tube 218 which is embedded in a children's balance bike frame 210 .

The rear wheel 240 is received between a pair of rear wheel stays 213 and fixed to the rear wheel mounts 214 thereof. The rear wheel stays 213 extend slightly obliquely rearward from an upper apex of the child balance bike frame 210 .

By choosing a front wheel 230 whose diameter is larger than the rear wheel 240, a main tube 211 of the children's balance bike frame 210 can drop more steeply from the head tube 218 to a front apex 211.2 and then in the limited distance between the two wheels 230, 240 too rise once to a higher apex than would be the case with wheels of the same size. This step, which is inserted at the front apex 211.2 in the course of the children's balance bike frame 210, enables a low entrance in front of a saddle 250.

The saddle 250 is guided in a seat tube 215 with its seat post 251 . The seat tube 215 is passed through the main tube 211 of the child balance bike frame 210 . In order not to make the node at which the seat tube 215 and the main tube 211 of the children's balance bike frame 210 are combined too thick and - with regard to the production using the plastic injection molding process - to avoid material accumulations, the cross section of the children's balance bike frame 210 below the saddle 250 is kept slim. Only one stiffening rib 217 is provided there, which extends from the front apex 211.2 to a point behind the seat post 215, at which the children's balance bike frame 210 branches into the two rear wheel struts 213. The stiffening rib 217 encloses the lower end of the materially embedded seat tube 215 on both sides.

2A shows the children's impeller frame 210 in a side view without other parts of the impeller. The section between the head tube 218 and the seat tube 215 is referred to as the main tube 211 . This is designed as a thermoplastic hollow profile that is manufactured using fluid injection technology. It is divided into a main section 211.1, which runs from the head tube 218 to the front apex 211.2, and into a secondary section 211.3, which extends between the front apex 211.2 and the seat tube 215. The area of the main tube 211 embodied as a hollow profile ends just behind the seat tube 215 .

2 B shows the same view as in 2A , where the most important angles α, β, γ for the children's balance bike frame geometry are shown. The seat tube 215 is, as is generally customary, inclined at an angle γ of 10° to 15° to the vertical, so that with increasing body size not only the seating point is increased, but also the distance to the handlebars is increased. The main section 211.1 and the secondary section 211.2 of the main pipe 211 enclose an angle α which is at least 80°. A significantly smaller angle should be avoided here in order to avoid stress concentrations. The secondary section 211.3 and the rear wheel struts 213 enclose an angle β of 110° to 140°.

3 shows the children's balance bike frame 210 in a perspective representation obliquely from below. A recess 218.1 can be seen on the control tube 218, which can be used to feed through brake cables or electrical lines or the like. The structure of the reinforcing rib 217, which encloses the seat tube 215, is clearly visible.

4 shows a children's bicycle 100 in a side view, which has two wheels 130, 140 of different sizes in the exemplary embodiment. The front wheel 130 is fitted to a front wheel mount 121 of a front wheel fork 120 . This is connected to a link 124 . The front fork 120 and handlebar 124 unit is guided through a head tube 118 which is embedded in a children's bicycle frame 110 . A bottom bracket mount 112 is formed at the bottom of the children's bicycle frame 110 . A saddle 150 is guided with its seat post 151 in a seat tube 115 which is embedded in the children's bicycle frame 110 . The rear wheel 140 is accommodated between chain stays 113 and seat stays 116 and is fastened to rear wheel mounts 114

• - einen Hauptabschnitt 111.1, der vom Steuerrohr 118 aus bis zu einer vorderen Verzweigungsstelle 111.2 verläuft,
• - einen Oberrohrabschnitt 111.3, der sich von der vorderen Verzweigungsstelle 111.2 bis zum Sitzrohr 115 erstreckt;
• - einen Unterrohrabschnitt 111.5, der sich als Fortsatz des Hauptabschnitts 111.1 von der vorderen Verzweigungsstelle 111.2 bis zu der Tretlageraufnahme 112 erstreckt.

5A shows the children's bicycle frame 110 in a side view. The section between the head tube 118, the seat tube 115 and the bottom bracket 112 is hollow by means of fluid injection technology. The hollow part of the children's bicycle frame 110 is divided into:

• - a main section 111.1, which runs from the control tube 118 to a front branch point 111.2,
• - A top tube section 111.3, which extends from the front branch point 111.2 to the seat tube 115;
• - A lower tube section 111.5, which extends as an extension of the main section 111.1 from the front branching point 111.2 to the bottom bracket mount 112.

• - ein Paar von Sitzstreben 116, die hinter dem Sitzrohr 115 abzweigen und jeweils an einer Hinterradaufnahme 114 enden und
• - ein Paar von Kettenstreben 113, die sich jeweils von einem Bereich an oder hinter der Tretlageraufnahme 112 bis zu der Hinterradaufnahme 114 erstrecken.

In addition, the children's bicycle frame 110, which is manufactured as a one-piece plastic injection molded part, has the following molded sections:

• - A pair of seat stays 116 branching off behind the seat tube 115 and each ending at a rear wheel mount 114 and
• - A pair of chainstays 113, each extending from an area at or behind the bottom bracket 112 to the rear wheel 114.

By choosing a front wheel 130 whose diameter is larger than the rear wheel 140, the main section 111.1 of the main tube 111 can drop steeply from the head tube 118 to the front branch point 111.2 and then rise to the upper apex 111.4. This step, which is inserted in the course of the main section 111.1, enables a low entrance in front of a saddle 150.

• - dem Oberrohrabschnitt 111.3 zwischen der vorderen Verzweigungsstelle 111.2 und dem Sitzrohr 115;
• - dem Unterrohrabschnitt 111.5 zwischen der vorderen Verzweigungsstelle 111.2 und der Tretlageraufnahme 112 und
• - dem Sitzrohr 115, das am oberen Scheitelpunkt 111.4 form- und/oder stoffschlüssig mit dem Kinderfahrradrahmen 110 verbunden ist und das sich mit seinem unteren Ende an der Tretlageraufnahme 112 abstützt oder damit fest verbunden ist.

In particular, the triangle of forces is important, which is composed of:

• - The top tube section 111.3 between the front branch point 111.2 and the seat tube 115;
• - The lower tube section 111.5 between the front branch point 111.2 and the bottom bracket mount 112 and
• - The seat tube 115, which is positively and/or cohesively connected to the child's bicycle frame 110 at the upper vertex 111.4 and which is supported at its lower end on the bottom bracket mount 112 or is firmly connected thereto.

5B shows in the same view as in 5A the children's bicycle frame 110 again from the side, with the essential angles α, β', γ' being indicated. The top tube section 111.3 has a similar profile to the children's balance bike frame 210 described above. The introduction of the weight of the child at the upper apex 111.4 is advantageous for the stability of the children's bike frame 110 with a simultaneously low mass, since the bending stresses acting on the top tube section 111.3 are lower than in one of the conventional prior art geometries where the seat tube meets the top tube approximately perpendicularly. According to the invention, the seat stays 116 and the top tube section 111.3 enclose an angle β' of 110° to 140°. The main section 111.1 and the top tube section 111.3 enclose an angle α′ of at least 80°.

6 12 is a further perspective view of the children's bicycle frame 110. It can be clearly seen here that the seat tube 115 has a smaller diameter compared to the other sections of the children's bicycle frame 110 made of plastic and is passed through them. A receptacle 111.6 is formed on the top tube section 111.3, in the region of the upper apex 111.4, in order to accommodate the part of the seat tube 115 protruding from the top tube section 111.3. At this point, a positive and/or material connection of the seat tube 115 to the children's bicycle frame 110 is provided. Mounts 116.1 for a brake are embedded on the chainstays 116.

7 shows a perspective view of the children's bicycle frame 110 from below at an angle. In the sections of the top tube section 111.3 and the down tube section 111.5, which each extend between the seat tube 115 and the point where the branching into the seat stays 116 or chain stays 113 begins, reinforcement structures 117, 119 are formed. The chain stays 113 and the seat stays 116 are each formed with smooth walls at the sides and at the top. They are open at the bottom and reinforced with a ribbed structure. A stand receptacle 113.1 for a bicycle stand is formed on at least one of the chain stays 113.

8th shows a partial section of the children's bicycle frame 110 in a perspective view. Seat tube 115 and bottom bracket 112 together form a hammer-like configuration. The seat tube 115 is supported at the top in the dome-shaped receptacle 111.6; the bottom bracket mount 112 rests in the children's bicycle frame 110 at the bottom. Loads that are introduced via the seat tube 115, which has a small diameter compared to the width of the sections 111.1, 111.3, 111.5 of the child's bicycle frame 110. Forces can thus be directed to the cylindrical wall of the bottom bracket mount 112 and are therefore distributed over a larger area at the transition to the plastic frame.

A reinforcement structure 111.7 with reinforcement ribs is formed behind the receptacle 111.6, before the two seat stays 116 branch off. The reinforcement structure 117 is provided behind the bottom bracket mount 112 and in front of the branching into the two chain stays 113 .

In 9 the area of the rear wheel mounts 114 is shown. The chain stay 113 and the seat stay 116 do not join with each other there. Instead, a rear wheel attachment unit 160 is provided. This consists of an inner disk 164, an axle guide element 162, an outer disk 163 and a cover cap 161. The axle guide element 162 is made of metal in order to absorb the high selective surface pressure of the rear axle guided through it and to transfer it to the thermoplastic bicycle frame. It is inserted directly between chain stay 113 and seat stay 116 and secured in place by bolting washers 163, 164 together. The rear wheel is then fastened in the usual way by placing nuts on the ends of the axle, which are braced against a shoulder on the axle. The axle guide element 162 also has an extension 162.1 which allows the attachment of a mudguard or a luggage rack. A cap 161 covers the other parts of the rear wheel attachment unit 160 and a nut placed on the rear wheel axle.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102006007862 A1 [0004]
• EP 2964514 B1 [0006]

Claims (13)

Children's balance bike frame (210) at least comprising: - a head tube (218) for receiving a front wheel fork (220) and a handlebar (224); - A seat tube (215) for receiving a seat post (251); - a main tube (211) connecting the head tube (218) and the seat tube (215); - A pair of rear wheel struts (213), each of which extends from an area on or behind the seat tube (215) to a rear wheel mount (214) and form a rear wheel fork, characterized in that - the children's balance bike frame (210) is a one-piece plastic Injection molded part is formed, wherein at least the main pipe (211) is hollow; - that the main tube (211) falls in a main section (211.1) from the head tube (218) to a lower apex (211.2) lying in front of the seat tube (215); - that the main pipe (211) rises from the lower apex (211.2) in a secondary section (211.3) to an upper apex (211.4); - that the seat tube (215) is guided through the upper apex (211.3) and - that the rear wheel struts (213) fall downwards from the upper apex (211.4) to the rear wheel mount (214). Children's balance bike frame (210). claim 1 , characterized in that the control tube (218) and/or the seat tube is (are) designed as metal profile(s) which is (are) embedded in the base frame element (210) in a cohesive manner. Children's balance bike frame (210). claim 1 or 2 , characterized in that above the lower apex (211.1) and/or below the upper apex (211.3) at least one reinforcing rib (217) extending in the longitudinal direction of the children's balance bike frame (210) is formed on the main tube (211). Children's impeller frame (210) according to one of Claims 1 until 3 , characterized in that - that the longitudinal axes of the main section (211.1) and the secondary section (211.4) enclose an angle α of 80° to 100° and - that the rear wheel struts (213) form an angle with the secondary section (211.3) of the main tube (211). include β from 125* to 150°. Children's balance bike (200), at least comprising: - A children's balance bike frame (210) according to any one of the preceding claims; - A front wheel (230) which is inserted at a front wheel mount (221) into a front wheel fork (220) which is connected to a handlebar (224), the unit made up of the front wheel fork (220) and handlebar (224) in the head tube ( 218) is guided. - A rear wheel (240) received between a pair of rear wheel stays (213) and attached to the rear wheel mounts (214). Balance bike (200) after claim 5 , characterized in that the front wheel (230) has a larger diameter than the rear wheel (240). Children's bicycle frame (110), at least comprising: - a head tube (118) for receiving a front wheel fork (120) and a handlebar (124); - A seat tube (115) for receiving a seat post (151); - a bottom bracket (112); - A pair of seat stays (116) each extending from an upper portion of the seat tube (115) to a rear wheel mount (114), - A pair of chain stays (113) extending from the bottom bracket mount (112) to a Rear wheel mount (114), characterized in that - that the children's bicycle frame (110) is designed as a one-piece plastic injection molded part, at least one section of the children's bicycle frame (110), the head tube (118), the seat tube (115) and the bottom bracket ( 112) connects to each other, is hollow; - that the hollow part of the children's bicycle frame (110) is divided into: ◯ a main section (111.1), which runs from the head tube (118) to a front branch point (111.2), ◯ an upper tube section (111.3), which extends from the front Branch point (111.2) extends to an upper apex (111.4), at which the seat tube (115) is arranged. ◯ a lower tube section (111.5), which extends as an extension of the main section (111.1) from the front branch point (111.2) to the bottom bracket mount (112). Children's bicycle frames (110) according to claim 7 , characterized in that the top tube section (111.3) is supported on the bottom tube section (111.5) via the seat tube (115) and the bottom bracket mount (112). Children's bicycle frames (110) according to claim 7 or 8th , characterized in that the head tube (118) and the seat tube (115) are designed as metal profiles which are materially embedded in the children's bicycle frame (110). Children's bicycle frame (110) according to one of Claims 7 until 9 , characterized in that an upper end of the seat tube (115) form is firmly supported by a receptacle (111.6) formed on the top tube section (111.3) at the upper vertex (111.4). Children's bicycle frame (110) according to one of Claims 7 until 10 , characterized in that - that the longitudinal axes of the main section (211.1) and the top tube section (111.3) enclose an angle α of 80° to 100° and - that the seat stays (116) with the top tube section (111.3) form an angle β of 125° to include 150°. Children's bicycle (100) at least comprising: - a children's bicycle frame (110) according to any one of the preceding Claims 7 until 11 ; - A front wheel (130), which is inserted into a front wheel fork (120) on a front wheel mount (121), which is connected to a handlebar (124), the unit consisting of the front wheel fork (120) and handlebar (124) in the head tube ( 118) is guided. - A rear wheel (140) which is attached to the rear wheel mounts (114). Children's bike (100) after claim 12 , characterized in that the front wheel (130) has a larger diameter than the rear wheel (140).

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