EP0000553B1 - Two-wheeled bicycle-type vehicle - Google Patents

Description

The invention relates to a bicycle-like two-wheeled vehicle with a frame consisting of four articulated parts, of which the upper frame part carries a saddle, the front frame part a rotatably mounted front fork connected to a handlebar and the lower frame part carries the rear wheel and the driving sprocket of a chain drive , footrests are attached to the front or lower frame part and a connecting rod articulated on both sides is arranged between the upper frame part and a crank which is connected to the driving sprocket in a rotationally fixed manner.

Usually, the frame parts of bicycles are welded or screwed to one another and to the struts of the rear wheel fork. The drive takes place in a known manner by means of foot force via pedals connected to the driving sprocket. The saddle and the front fork bearing are fixed relative to each other and to the frame.

Numerous bicycle-like two-wheeled vehicles have also become known, in which the saddle, handlebar axle and bottom bracket are movable relative to one another and the rider's feet are moved parallel to one another (see, for example, DE-C-57 280, DE-C-662 428, GA457 307 , US-A-1 377 886). However, a fixed frame usually carries both the rear wheel and the front fork, so that the wheelbase remains constant while driving. Various additional levers and cranks are rotatably mounted on the rigid, load-bearing frame, which convert the forces exerted alternately on the saddle and the footrests into a drive torque. All of these constructions have the disadvantage that they are necessarily relatively heavy because, like a bicycle, there must be an inherently stiff, stable frame and, in addition, a much more complicated and heavy drive mechanism compared to the bicycle.

It is also already known (CH-A-248 369) to dispense with the rigid, load-bearing frame and instead to provide a frame consisting of four parts which are connected to one another in an articulated manner and act on the chain drive via a connecting rod, the same frame parts having two functions simultaneously can take over, namely to carry and also form a drive lever system. In this way, the frame parts are used twice and long levers are available for the drive ratio without additional weight. Since all frame parts move up and down as well as back and forth with respect to the wheel axles while the handlebar is participating in this movement, the driver can generate an additional drive torque by pulling back and pushing the handlebar.

Because propulsion takes place alternately in two phases in a vehicle of the type mentioned at the beginning, while the driver shifts his weight onto the saddle and then onto the footrests and the saddle and footrests move up and down in opposite directions, the driving characteristics are crucial assumes that the propulsion is approximately the same in both phases, because when driving uphill the maximum gradient is determined solely by the phase with the weaker propulsion and, in addition, driving is generally found to be more pleasant if the body movements are uniform in both phases. If one assumes that the saddle and then the footrests are alternately loaded with approximately the same force depending on the weight of the rider, the strokes of the saddle and the footrests should not be too different, so that in both phases the same mechanical work approximates performed and the same torque is generated on the rear wheel.

In the known vehicle with four-part frame frame, the lower frame part ends at the rear wheel axle. The rear frame part extends from a joint arranged at the rear end of the lower frame part directly next to the rear wheel axle to a joint formed shortly before the saddle on the upper frame part. Taking into account the constructive limits set by human body dimensions, only a small stroke of the saddle, combined with an uncomfortably strong inclination, can result in such a design, so that the vehicle, even on the smallest inclines, always in the phase in which the If the saddle is loaded, it stops and higher speeds cannot be reached even in the plane.

The invention has for its object to improve a vehicle of the type mentioned in such a way that the sequence of movements over both drive phases is more uniform and harmonious and thereby the driving performance is improved.

The above object is achieved in that the lower frame part extends with its rear end beyond the rear axle and acts as a two-armed lever.

Due to the proposed extension of the lower frame part to the rear beyond the rear wheel axle, there is an additional lever arm available, which significantly increases the stroke of the saddle during the pivoting movements of the lower frame part and a moment arm for those exercising on the saddle Power builds. Because in this way the lifting movement of the saddle is generated essentially by the lower and rear frame part, the upper frame part does not need to be tilted so much and the inclination of the saddle can be minimal. The pleasant driving experience also contributes significantly to the fact that due to the balanced driving characteristics in both drive phases, the body movements of the driver are even, i.e. he hovers while stretching his legs and pulling them back up and down evenly, and it is avoided that he The footrests are jerkily pressed down quickly, but then very slowly when the saddle is loaded in the body and driving movement. The balance of forces and movements in both phases in connection with the pivoting movement of the handlebar in the direction of travel gives the driver the impression of riding.

In a preferred embodiment of the invention, the lower frame part extends beyond the rear wheel axis to such an extent that the joint between the rear and the lower frame part is located radially outside the rear wheel. Given the external dimensions of the vehicle, this results in the longest possible lever arm which increases the stroke of the saddle and the drive torque, and the essential advantage for the rigidity and robustness of the frame is obtained that the lower frame part is integrally connected by two at the rear end by a web parallel struts can exist and a single simple bearing between the lower and the rear bearing part is sufficient.

To overcome the dead center of the driving movement between the two alternating movement phases, it is advantageous if there is a rotationally fixed connection between the rear wheel and the driving sprocket by means of the chain. The rear wheel then drives the front sprocket in the area of the dead centers. On the other hand, because of the large lifting height of the saddle achieved according to the invention, it may be desirable to let the vehicle roll without the saddle lifting and lowering. In order to enable such a driving state, an arbitrarily releasable clutch or an adjustable slip clutch can be arranged between the driven sprocket and the rear wheel in an expedient development of the invention. A gear shift can be provided as a further embodiment.

Special measures must be taken if, also for occasional suspension of the large lifting movements of the saddle, the rear wheel has a freewheel hub, as occurs in bicycles with and without back pedaling as well as with open or hub gear shifting or also without gear shifting. Since in all these cases the freewheel does not generate a sufficiently strong drag torque to overcome the two dead positions in which the crank and the connecting rod are aligned, in this application the preferred embodiment of the invention is a spring mechanism acting between the connecting rod and a frame part provided, which preferably consists of an articulated with the rear frame part or the connecting rod and with the other of these two parts via at least one rod connected.

By jacking up the new device, it can also be used as a so-called home trainer, for the sake of simplicity the rear wheel can be replaced by a flywheel and the front wheel can be replaced by a rolling, sliding or articulated guide supporting the front frame part.

• Fig. 1 eine schematische Seitenansicht einer ersten Ausführungsform der Erfindung,
• Fig. 2 in Seitenansicht ein gegenüber Fig. 1 abgewandeltes Ausführungsbeispiel,
• Fig. 3 a, b einen Querschnitt und eine Seitenansicht eines Gelenks des Fahrzeugrahmens,
• Fig. 4 einen Teilschnitt durch eine Hinterradnabe, die zur Verwendung bei den Fahrzeugen nach Fig. 1 und 2 geeignet ist.

The invention is explained below with reference to the drawing. Show it:

• 1 is a schematic side view of a first embodiment of the invention,
• 2 shows a side view of a modified embodiment compared to FIG. 1,
• 3 a, b a cross section and a side view of a joint of the vehicle frame,
• Fig. 4 is a partial section through a rear wheel hub, which is suitable for use in the vehicles of FIGS. 1 and 2.

In the drawing figures, corresponding parts have the same reference numerals.

The vehicle shown as an exemplary embodiment in FIG. 1 corresponds to a normal bicycle with regard to the wheels 10, 12, the front wheel fork 14 and the handlebar 16. The saddle 18 and the chain drive, consisting of a front, driving sprocket 20, a driven sprocket 22 seated on the axle of the rear wheel and a chain 24, are also commercially available parts. The same applies to normal bicycle accessories, such as Mudguards, lamps and smoke lamps, brakes and gear shift, luggage rack and the like.

A special feature of the new vehicle are the numerous joints between the different parts of the frame. All of the joints shown have a horizontal axis of rotation.

Specifically, the frame consists of an upper frame part 26 which is connected to a front frame part 30 via a joint 28. The latter includes the bearing of the front fork 14 and the handlebar 16. In addition, a rear frame part 32 is connected to the upper frame part 26 via a joint 36, which in turn is connected to a lower frame part 34 via joints 42. The latter is also articulated on the front frame part 30 via a joint 38. The rear frame part 32 and the lower frame part 34 each consist of struts which are arranged in parallel on both sides of the rear wheel. The struts of the lower frame part 34 extend with their rear end 44 beyond the rear wheel axle 40. The back end 44 can, for example, be bent or angled upwards by 10 to 60 °.

In the exemplary embodiment, the joint 38 is separated from the bearing of the driving sprocket 20 designated 46 for manufacturing reasons. This bearing is fixedly attached to the lower frame part 34, so that the center distance between the two sprockets 20, 22 is constant. With the sprocket 20 a crank 48 is rotatably connected to both sides of the bearing 46 as shown in FIG. 1. Both cranks extend from the bearing 46 in the same direction and are of the same length. Each crank 48 is connected via a joint 50 attached to its free end to a connecting rod 52 which engages at the upper end via a joint 54 on the upper frame part 26. The joints 36 and 54 are secured in the example by means of clamps 56 and 58 on the upper frame part 26, so that they can be adjusted along the tube which forms the upper frame part 26. The saddle 18 is likewise adjustable along the upper frame part. The joint 28 is also adjustable by means of a clamp 62.

Height-adjustable footrests 60 are attached to the front frame part 30 in the lower region. As can be seen, in the movement phase in which the driver rests his weight on the footrests 60, the bearing 46 of the driving sprocket 20 together with the front frame part 30 is pressed down with respect to the lower joint 50 of the connecting rod 52. After the bottom dead center has been exceeded, the bearing 46 is then raised again with reference to the joint 50 when the driver in the next phase of movement shifts his weight more strongly onto the saddle and, via the rear frame part 32, the lower frame part 34 to support it on the rear wheel axle 40 pivoted counterclockwise with reference to the drawing.

The rotation of the bearing 46 around the joint 50 means, because of the rotationally fixed connection between the driving sprocket 20 and the cranks 48, a rotation of the sprocket 20, as a result of which the drive to the rear wheel takes place. Furthermore, the cyclical movement of the crank 48 and the connecting rod 52 brings with it an alternating spreading and narrowing of the articulated quadrilateral formed from the frame parts 26, 30, 32, 34, which leads to the desired relative movement between the. Saddle 18, the handlebar 16 and the footrests 60 'leads.

In a practical embodiment with 26-inch wheels, the upper frame part 26 can have a length of 85 cm and the front frame part 30 between the joints 28 and 38 can have a length of 60 cm. The connecting rods 52 are 38 cm in the example, the cranks 48 are 12 cm, the struts of the rear frame part 32 are 40 cm and the struts of the lower frame part 34 are 37 cm between the joint 38 and the rear wheel axle 40 and in the rear section 44 18 cm long. The distances between the joints on the upper frame part 26 can e.g. be adjusted so that the distance between the joints 28 and 54 is 50 cm and the distance between the joints 54 and 36 is 25 cm. The joints 42 and 50 contain ball bearings, while the joints 28, 36, 38 and 54 are designed according to FIG. 3 a, b. This will be discussed further below.

The embodiment according to FIG. 2 corresponds essentially to the embodiment according to FIG. 1 with regard to the upper frame part 26 and the front frame part 30. One difference, however, is that the lower frame part 34, 44 is a single coherent part because the two side parts are behind the rear wheel united by a web part connecting them. This construction gives the frame greater rigidity and allows, instead of 2 joints 42 with ball bearings, a single joint with a plastic bushing according to FIG. 3a to be used. In addition, the greater length of the rear part 44 of the lower frame part 34 compared to FIG. 1 leads to a coarser drive torque in the phase of movement where the weight rests on the saddle.

At its front end, the lower frame part 34 is extended beyond the joint 38 and bent downwards. The footrests 60 are attached there in this embodiment. Compared to FIG. 1, this also includes an improvement in the lever transmission effective when driving as in the arrangement of the bearing of the driving sprocket 20 in front of the joint 38, as shown in FIG. 2.

In a practical embodiment with 26-inch wheels, the vehicle according to FIG. 2 has the following dimensions: the rear part 44 of the lower frame part 34 is 38 cm, the cranks 48 are 17 cm, the connecting rods 52 are 46 cm and the other frame parts as long as indicated above for Fig. 1. The articulated angle of the lower frame part 34, 44 designated a is approximately 50 °.

For a description of the joints of the frame, reference is made to FIGS. 3a, b. There, the one of two articulated frame parts is designated A, while the other frame part, each consisting of two struts, is designated B ₁ and B _z .

In the case of the joints 34, 54 and 28, the upper frame part 26 is represented by part A in FIG. 3a, while the parallel struts of the rear frame part 32 or the connecting rods 52 and parallel tabs on the clamp 62 (FIG. 1 ) or corresponding tabs which are welded to the front frame part 30 (FIG. 2) in FIG. 3 a are symbolized by the reference symbols B _{1 ′} B ₂ .

With regard to the joint 38, the part A means the front frame part 30, and the struts B _{1 '} B ₂ represent the lower frame part 34 In the case of the joint 42 according to FIG. 2, part A corresponds to the web which connects the two side parts of the lower frame part 34, 44 to one another, while B _{1 ′} B ₂ denotes the parallel struts of the rear frame part 32.

According to FIG. 3 a, a tubular bearing housing 64 is fixedly connected to the frame part A, for example welded. It contains a bearing bush 66 made of polyamide or another plastic suitable as a bearing material. A bolt 68 extends through the bushing 66 and is rotatably supported therein. As shown, the bolt 68 is a little longer than the bushing 66 and the bearing housing 64. The struts B _{1 '} B ₂ are by screws 70 which extend through holes in the struts B _1' B ₂ and into a central threaded bore in the Bolts 68 are screwed, firmly connected to this.

The lever mechanism formed by the articulated frame, the cranks 48 and the connecting rods 52 has two dead positions which have to be overcome with each revolution of the chain wheel 20 during normal travel. This is not a problem when the rear sprocket 22 is non-rotatably connected to the rear wheel 12, but requires special precautions if it is desired to do so while driving, e.g. downhill to stop the up and down movement of the saddle, but continue to roll with the vehicle. Two possible solutions to this problem are explained below with reference to FIG. 4. Fig. 2 then shows yet another proposal.

To ensure on the one hand the overcoming of the dead positions, on the other hand to stop the movements of the saddle, the footrests and the handlebars while driving, the embodiment according to FIG. 4 uses a friction clutch 76 and 78 consisting of two interacting friction disks, which during normal driving the drag torque from the hub of the rear wheel 12, designated 72, from which only spokes 74 are indicated in FIG. 4, to the sprocket 22 - in a vehicle with an open gearshift, the sprocket 22 is replaced by a block of e.g. 3 or 5 different sized sprockets replaced-transmits. The sprocket 22 is axially slidable, but e.g. held non-rotatably on a surface by means of a wedge. pin-shaped part 73 of the hub 72 and, in a conventional design, consists of two parts 23 and 25 arranged radially one above the other, which are coupled by a freewheel, not shown. The friction disk 76 is non-rotatably fixed to the hub 72 by means of two or more welded-on pins 80, while the friction disk 78 is non-rotatably connected to it in the same way via welded-on pins 80 which engage in holes or slots in the radially outer part of the chain wheel 22. The greatest torque that the clutch 76, 78 can transmit is determined by a plate spring 82 inserted between the friction disk 78 and the chain wheel 22, which is tensioned by a nut 84 screwed onto the fixed axle 40 of the rear wheel 12. The nut presses on the plate spring 82 via the radially inner part 23 of the chain wheel 22 and possibly via a bearing washer reducing the friction between these two parts or an axial roller bearing 81. Axial outside of the nut 84 is then, as shown in FIG. 4, the axle 40 of the rear wheel is firmly connected to the lower frame part 34.

The friction between the two friction disks 76 and 78 need not be great in order to overcome the dead positions mentioned. The bias of the plate spring 82 can be adjusted with the help of the nut 84 by a single adjustment for a long time so that the two friction disks 76, 78 always slide against each other when the driver desires and for this purpose his weight opposite to the movement phase of the saddle un relocated to the footrest, e.g. in a phase where he should actually let his weight work on the saddle, the footrests are loaded.

A further alternative embodiment of the invention can be explained with reference to FIG. 4. Instead of a slipping clutch that is set to a specific maximum torque, a releasable clutch can also be used. For this purpose it can be provided that the pressure on the friction disks 76, 78 can be changed while driving, e.g. the nut 84 is firmly connected to a lever 85 on which a Bowden cable to be actuated by the driver engages. The pulling wire of the Bowden cable acts in the loosening direction of rotation on the lever 85 and the nut 84, while in the opposite direction of rotation, i.e. in the direction of greater pretensioning of the plate spring 81, another clamped between the lever 85 or the nut 84 on the one hand and the rear frame part 34 on the other hand Spring 83 acts. The bias of the spring 83 is adjusted so that the clutch 76, 78 never slips regardless of whether the driver shifts his weight correctly or incorrectly. Only when the driver turns the nut 84 against the action of the spring 83 in the release direction by means of the bow pull and the lever 85 can the friction disks 76, 78 slide against each other, so that the saddle stops moving up and down while driving. When using a strong releasable clutch, instead of a sprocket with a freewheel that is firmly seated on the wheel hub, a simple sprocket that rotates on the hub can be used.

2 contains a normal freewheel hub with coaster brake. The hub can optionally also include a three-speed gearbox. Alternatively, a normal freewheel hub without back pedaling can also be used brake with or without gear shift of any design can be used. Since normal freewheel hubs only develop a minimal drag torque, which is not sufficient for overcoming the above-mentioned dead positions, FIG. 2 shows a construction which solves the problem of dead positions in a different way. It is assumed that the distance between two specific points on the one hand on the rear frame part 32 and on the other hand on the connecting rod 52 is small in the dead position in which the saddle is in its highest position and large in the dead position in which the saddle has the lowest position. If, under these conditions, a rod designated by 86 in FIG. 2 is articulated to the rear frame part 32 and is guided, for example, by means of a roller 88 mounted on the upper frame part 26 in such a way that it extends at least in the uppermost position of the saddle forward over the connecting rod 52 extends beyond, there is the possibility to span two tension springs 90, 92 in such a way between the rod 86 and the connecting rod 52 that, for example, the spring 92 is strongly tensioned and at the same time the spring 90 is relaxed when the saddle is in its highest position , on the other hand, the spring 90 is under strong tension and the spring 92 is relieved, while the saddle occupies the lowest position. In this construction, one of the two springs then ensures that the connecting rod 52 is moved out of the dead position again.

Practically the same result can also be achieved with only a single spring, which takes about a middle position between the two springs 90 and 92 and is then tensioned both when the saddle moves to its highest position and when it moves to its lowest position Position is approaching.

It goes without saying that there is great freedom of design in the shaping of the individual frame parts, the joints and the rear wheel hub. For the sake of simplicity, the frame parts are shown and described essentially as straight steel tubes. As with bicycles, curved shapes, panels, etc. are of course also possible. Dimensional deviations from the dimensions mentioned above by way of example entail certain changes in the relative movements, speeds and accelerations, which, however, do not affect the basic functionality in a relatively wide range. After some dimensions of the frame have been determined, one can find by moving the hinge points, e.g. by means of clamps, as described in connection with FIG. 1, in each case very quickly the optimal position of the joints, at which the effort required when driving is the least and / or the oscillating movement with its changing accelerations is most harmonious. In series production, the clamps can then be replaced by permanently welded joint parts, e.g. shown in Fig. 3 a. An essentially U-shaped, elastic bracket can be provided as the lamp holder, which is attached directly behind the bearing of the handlebar with one leg to part 26 and the other leg to part 30.

Claims (10)

1. Two-wheeled bicycle-type vehicle with a frame consisting of four pivotably interconnected frame members (26, 30, 32, 34) of which the upper frame member (26) carries a saddle (18),- the front frame member (30) is provided with a bearing for a rotatable front wheel fork (14) connected to a steering handle (16) and the lower frame member (34) carries the rear wheel (12) and the driving sprocket wheel (20) of a chain drive (20, 22, 24), the front frame member (30) or the lower frame member (34) being provided with pedals (60) and a connecting rod (52) extending between and being pivotably connected to the upper frame part (26) and a crank arm (48) fixed to the driving sprocket wheel (20), characterized in that the lower frame part (34) with its rear end extends beyond the rear wheel axle (40) and functions as a two-armed lever.

2. Vehicle according to claim 1, characterized in that the joint (42) between the rear frame part (32) and the lower frame part (34) is located radially outside of the rear wheel (12).

3. Vehicle according to claim 2, characterized in that the lower frame part (34) consists of two integral parallel rods interconnected at their rear ends by a bridge the rear wheel being held between these rods.

4. Vehicle according to one of claims 1 to 3, characterized in that the lower frame part (34) behind the rear wheel axle (40) has a bend or angle directed upwardly by about 10° to 60°.

5. Vehicle according to one of claims 1 to 4, characterized in that axially on both sides of the bearing (46) of the driving sprocket wheel (20) there is provided in parallel disposition one crank arm (48) and one connecting rod (52).

6. Vehicle according to one of claims 1 to 5, characterized in that the joint (38) connecting the front frame part (30) and the lower frame part (34) is located coaxially with the bearing (46) of the driving sprocket wheel (20).

7. Vehicle according to one of the claims 1 to 5, characterized in that at the lower frame part (34) the bearing (46) of the driving sprocket wheel (20) is located in the front of the joint (38) between the front frame part (30) and the lower frame part (34).

8. Vehicle according to one of the claims 1 to 7, characterized in that in combination and in parallel with a free-wheel mechanism in the transmission (25, 23, 73) between the driven sprocket wheel (22) of the chain drive (20, 22, 24) and the hub (72) of the rear wheel (12) there is provided a friction clutch (76, 78) of the type of a safety clutch or being disengageable at will.

9. Vehicle according to one of the claims 1 to 7, characterized in that in combination with a free-wheel mechanism in the transmission (25, 23, 73) between the driven sprocket wheel (22) and the hub (72) of the rear wheel (12) a spring force (90, 92) works on the connecting rod (52) trying to move it out of positions in parallel with the crank arm (48).

10. Vehicle according to one of the claims 1 to 9 in application as home-trainer, characterized in that a fly-wheel is provided instead of the rear wheel (12) and a stand supports the frame (26, 30, 32, 34) together with the fly-wheel, wherein the front frame part (30) is supported on the ground by means of a wheel (10) or a guide rail mounted on the stand.

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