DE29701641U1 - Folding bike with small wheels or castors - Google Patents

Description

Description: Folding bike with small wheels or rollers

State of the art:
for conventional folding bikes:

e.g. Moulton, Birdy, Brompton{see Encycleopedia 94/95 ISBN 1 898457 01 8 ),Bickerton portable,Hon Folder,(Moby Dick Verlag ISBN 3-922843-27-1)attempts are made to fold a bicycle so that it is as small as possible when packed. These folding bikes are usually equipped with a large number of folding, sliding and rotating elements. These elements require a certain amount of care when operating them. Several steps must be carried out one after the other until the bike is reduced in size or ready to ride again.This is particularly disadvantageous when taking it on public transport.In addition, each of these elements weakens or destabilizes the bike frame, or increases the weight with the same stability.Most folding bikes have a total weight of at least 10 kg.

Most folding bikes have a U-shaped overall frame when viewed from the side. Due to the excessive length of the handlebar, frame tube and seat, these bikes are not torsionally rigid. There are folding bikes that have better torsionally rigidity (eg Moulton (see Encycleopedia 94/95 ISBN 1 898457 01 8 ), but these have the disadvantage that they are quite difficult to put together or fold.
Issue :

My invention aims to create a bicycle that is largely equivalent to a "normal" bicycle in terms of its handling, but is also very light, has a high torsional rigidity and can be folded up in a very short time. This means that it should be particularly suitable for the conditions of urban life and for being taken on public transport. The aim was not to achieve the smallest possible packing size, but rather a packing size that can still be easily taken on the train or bus.

These problems are solved by the invention of the braced frame shape according to claim 1 in conjunction with small wheels.

achieved benefits:

The invention specified in claim 1 creates a folding bike that, although it has most of the properties of a normal bicycle (normal riding characteristics, stability), can be folded up very quickly and also has a very low weight. The X-shaped frame design has the advantage of being much more torsionally rigid compared to the conventional U-shape of known folding bikes, while using the same amount of material.

The braced construction also results in very positive spring properties for the entire vehicle. The folding bike weighs 7 kg in the first prototypes when it is built with conventional materials. Folding is very easy after loosening the safety rope by lifting the crossing point . The wheels of the bike can remain on the ground while folding. This means that you don't have to touch dirty parts in bad weather. The bike can also be pushed when partially or fully folded. It can also be carried easily when unfolded.

Several embodiments are explained using Figures 1 to 6. Bs show:

Fig. 1 the folding bike according to claim 1 side view ready to ride and folded

Fig. 2 the folding bike according to claim 2 side view ready to ride and folded

Fig. 3 the folding bike according to claim 2 ready-to-ride position in spatial view

Fig. 4 Spatial axis representation for all versions

Fig. 5 the folding bike according to claim 3 equipped with linear drive in a three-dimensional representation.

The further development of the invention according to the protection claim is described in more detail below.

In the drawing Fig. 2 and the spatial representation Fig. 3 an embodiment of the invention according to claim 2 is shown. The following explanation:

The vehicle shown is designed for use by an adult. It has 2 small wheels of about 30 cm in diameter, a conventional drive using a pedal crank and a chain drive on the rear wheel.

The riding geometry is roughly the same as that of a normal bicycle , with the exception that the bottom bracket is positioned a little further back.

The frame is constructed in such a way that four support elements are grouped around an intersection point, where they are movably connected to one another by means of hinge pins which are approximately perpendicular to the plane of the frame. According to claim 1, all 4 support elements meet at the intersection point. In the further development according to claim 2, however, the upper support element (3) is somewhat shortened and the rear wheel support element (6) is lengthened to the same extent, so that it is possible to dispense with a joint compared to the original basic construction. The support elements are each made of two tubes which are brought together in the direction of the steering bearings (7a, 7b) but widen in the direction of the intersection point 4. Single-tube constructions for the support elements (3, 4, 5) are also conceivable, if they have the appropriate reinforcement or widening towards the intersection point. However, I am more in favor of widening the intersection point because this saves material and therefore weight compared to a reinforcement measure. This widening of the entire frame in the area of the intersection point (18) in the direction of the spatial axis Y ensures that lateral forces, which are introduced into the cross-shaped frame via the steering bearings, the saddle and the bottom bracket, can be absorbed well, and the frame is thus torsionally rigid. Since the support elements (3,4,5) mainly have to absorb tensile and compressive forces, they are made thinner in comparison to the rear wheel support element (6). In a steel version, a dimension of approx. 12xlmm in cross section is sufficient. The rear wheel support element (6) is subject to strong torsional and bending forces, primarily due to moments introduced via the bottom bracket, which means that it needs to be dimensioned larger than the support elements (3,4,5) (approx. 30 x 30 mm). All support elements (3,4,5,6) are designed as tubular elements, but other closed hollow profiles can also be used.

If the folding axes (2) around which the support elements are grouped are arranged exactly perpendicular to the frame plane, the wheels and tires will collide with each other when folded.

To improve this, I arranged the folding axes slightly at an angle to the X-Z plane (approx. 7 degrees). The upper support element (3) and the lower support element (4) are attached to the steering column (1) via joints. Ball joints are conceivable here, or joints with an axis as a steering axis in the direction of the steering column (1) and another axis, which lies in the spatial direction Y as a pivot axis for the movable attachment of the support elements (3,4). As indicated in Figures 2 and 3, it is possible to place the steering bearings (7a, 7b) around the steering column (1), but the steering bearings (7a, 7b) can also be attached behind the steering column, similar to earlier so-called neck controls.

The upper tension element (16), the lower tension element (17) and the safety cable (19) are made of steel cables. Textile bands or cables can also be used instead of the steel cables; they result in a softer suspension behavior of the frame. An additional tension spring is also conceivable in conjunction with these tension elements in order to further increase the spring properties of the frame.

The tension elements (16, 17) are connected to the ends of the support elements (3, 4) on the side of the steering bearings (7a, 7b) so that they do not have to follow the steering movement. The safety cable (19) is only subjected to static loads in exceptional cases. When driving straight ahead normally, it is not necessary to give the frame the necessary stability. The loads that occur are lower than in the other tension elements. The safety cable is therefore the suitable place for a detachable fastening point. The safety cable can be released at the fastening point on the rear wheel support element (6) in order to initiate the folding process.

At least the tension element (16) which braces the seat support element (5) should be adjustable in length so that the saddle (15) can be adjusted in height (Z axis) to suit users of different sizes. In addition, the saddle should be adjustable along the seat support element (5) so that the position of the saddle can be corrected in the X direction when the height is adjusted.

The reference symbols mean:

(1) - Steering column, forms with fork, front wheel{13) and

Handlebar(8) one unit.

(2) - Folding axes

(3) - a support element

(4) - a support element

(5) - Seat support element

(6) *- Rear wheel support element, forms with bottom bracket (9) ,

Chainring (10) rear wheel{14) one unit (7a)- upper steering bearing {7b)- lower steering bearing

(8) - Handlebar

(9) - bottom bracket (10)- chainring (H)- chain (12)- pinion (13)- front wheel (14)- rear wheel (15)- saddle (16)- upper tension element (bracing) (17)- lower tension element (bracing) (18)- crossing point (19)- safety rope (20)- hinge pin (21)- folding joint

(30)- Drive cables (31)- Pedals (32)- Deflection pulley (33)- Straight guides (34)- Freewheel pulley

Claims (3)

Protection claims: 1. Claim Folding bike with small wheels or rollers with conventional seat geometry of the rider, conventional steering of the front wheel, caster of the front wheel, pedal crank or other drive, characterized in that a) the frame is formed from 4 support elements (3, 4, 5, &bgr;), which are movably connected to one another in the area of an intersection point (18) via one or more parallel folding axes (2), ,whereby these folding axes (2) are approximately perpendicular to the vehicle plane, i.e. in the X-Y plane. b) the 4 support elements (3, 4, 5, 6) are braced together during driving by at least two tension elements (16, 17) and the steering column (1) in such a way that an x-shaped or star-shaped frame structure is formed, which can now bear static loads. c) the connection of the support elements (3,4) to the steering column is made via joints which allow the steering movement on the one hand and the folding movement of the support elements (3,4) on the other hand. d) at least one of the two support elements (3, 4) can be folded into itself after releasing a safety lever via the folding joint (21), or can be released from its attachment to the associated steering bearing (7a, 7b), or the associated steering bearing can be moved on the steering column (1), so that all elements of the frame subsequently fold together into a longitudinal shape. e) the support elements (3,4,5,6) are designed so that they can transfer pressure and tensile forces to the crossing point (18). f) the support elements (3, 4, 5, 6) in the area of the crossing point (18) have, if possible, a spatial extension transverse to the vehicle plane (Y-axis) so that they are suitable for transferring moments which are introduced into the support elements by twisting of the frame in the steering bearings (7a, 7b) to the crossing point (18). g) the rear wheel support element (6) is suitable for transmitting pressure and tensile forces, but is also designed to be flexurally and torsionally rigid, i.e. it is larger in size than the other support elements (3, 4, 5). 2 . Claim 2. Folding bike according to claim 1, characterized in that h) the rear wheel support element (6) is extended in the direction of the upper steering bearing (7a) beyond the crossing point (18), and at the same time the support element (3) is shortened to the same extent, whereby the element for the section between the crossing point (18) and the folding joint (21) is not subjected to torsion and can therefore be designed as an open profile. i)the tension elements (16,17) consist of steel cables. j) The seat support element (5) and the rear wheel support element (6) are braced by a safety cable (19). k) the safety rope (19) or the upper tension element (16) is detachable. l) the folding axis (2) consists of several adjacent, approximately parallel axes (2) which are not exactly perpendicular to the frame plane (X-Z), but are slightly inclined in the direction of one of the two steering bearings (7a, 7b) so that when the frame is folded up, both wheels (13, 14) can be pushed next to each other. m) the bottom bracket (9) has a normal height compared to conventional bicycles, but is located relatively far back 3. Claim Folding bike according to claim 1 or 2
distinguished by the fact that &eegr;) a linear drive is used as the drive, in which two pedal elements (31) move on straight guides (33) along the drive support element (6) o) the pedal elements (31) are connected to traction cables (30) which exert a torque on the rear wheel via freewheel rollers (34) and one or more deflection rollers (32).