Front axle design for a bicycle with two front wheels

Abstract

Front axle construction for a bicycle with two front wheels (4) which are rotatably mounted in a fork (2) each, wherein the two forks (2) are rotatably attached to secondary head tubes (2.1) and a head tube extension (3) rotatably connected to the respective fork (2) by at least two cross members (7) which are arranged in two planes at a distance from each other, and the head tube extension (3) is arranged centrally between the secondary head tubes (2.1), and within the head tube extension (3) a steering tube (3.1) is rotatably mounted and the steering tube (3.1) can be connected to a handlebar (5), wherein Swivel joints (6) on the steering tube extension (3) and the secondary steering tubes (2.1) in two planes aligned parallel to each other and the planes are aligned parallel to the horizontal, characterized in that the head tube extension (3) can be guided through a head tube (17) of a frame (1) and is rigidly mounted therein or can be rigidly connected to the head tube (17) and a slave disc (8) is rotatably connected to the respective fork (2) and a master disc (9) is rigidly attached rotatably about a vertically oriented axis to the secondary steering heads (2.2) and to the steering tube (3.1). wherein at least one groove circumferentially around the radially outer surface of the slave disk (8) and at least two parallel grooves circumferentially around the radially outer surface of the slave disk (9) are formed, wherein at least one cable (10, 11) is guided in each of the grooves and the cables (10, 11) are attached to the slave disk (8) and to the slave disk (9) at one position.

Description

[0001] The invention relates to a front axle construction for a bicycle with two front wheels, which enables the conversion of single-track bicycles to multi-track bicycles.

[0002] Thanks to an integrated tilting mechanism and the retention of the original bicycle geometry, the concept is characterized by good cornering dynamics and the familiar, typical bicycle handling characteristics. The invention is suitable for retrofitting bicycles with conventional frame designs. The adaptive nature of the mounting solution also allows for quick conversion back to the bicycle's original state.

[0003] State-of-the-art technology for multi-track tilting bicycles, which can also be designed as cargo bikes, is currently gaining significant traction in the market. In most cases, the front axle is multi-track and the rear axle is single-track. Often, axle stub designs are used, which require a special frame design and, due to their atypical construction, do not accurately replicate the familiar handling characteristics of a bicycle.

[0004] Due to the axle design, the achievable steering angles are often very limited, resulting in an unusually large turning circle for the entire vehicle. Besides such solutions, multi-track mounting concepts are also known, which function on the principle of a turntable steering system. However, due to the resulting specific driving characteristics, these can prove to be very dangerous depending on the situation (sudden, unintended steering movements due to unevenly acting brakes, etc.).

[0005] For example, US 4 740 004 A describes a three-wheeled vehicle with two steerable front wheels that can be steered together.

[0006] GB 1910 / 11 300 A concerns a three-wheeled construction with crossbeams.

[0007] DE 10 2006 042 118 A1 concerns a two-wheeled front-mounted vehicle.

[0008] It is therefore an object of the invention to provide possibilities for equipping a bicycle with two steerable front wheels, with which safe cornering and preferably also easy conversion of a conventional bicycle with two wheels to a three-wheeled bicycle are possible.

[0009] According to the invention, this problem is solved with a front wheel axle construction having the features of claim 1. Advantageous embodiments and further developments of the invention can be realized with features specified in dependent claims.

[0010] A front wheel assembly according to the invention is designed such that two front wheels are provided, each rotatably mounted in a fork. The two forks are rotatably attached to secondary head tubes and a head tube extension, which is arranged centrally between the secondary head tubes, by means of at least two cross members arranged in two planes at a distance from each other. The head tube extension is rigidly connected to the frame by suitable means (e.g., tensioning with cables). A steering tube, which is rigidly connected to the handlebars, is freely rotatable within the head tube extension. Furthermore, pivot joints are located on the head tube extension and the fork crowns in two planes parallel to each other, and these planes are aligned parallel to the horizontal.

[0011] Advantageously, a total of four cross braces can be rotatably connected to the head tube extension and the secondary head tubes. A few of these cross braces should be positioned forward of the head tube extension and a few rearward of it, in the direction of travel. This achieves increased stability and a secure connection of the forks via the fork crowns, the cross braces, and the head tube extension. Furthermore, this improves power and torque transmission, especially during cornering.

[0012] A slave disc is rotatably mounted on each secondary steering head and a master disc is rotatably mounted on the steering tube about a vertically oriented axis. The slave discs should have at least one groove circumferentially around their radially outer surface, and the master disc should have at least two parallel grooves circumferentially around their radially outer surface. At least one cable is guided in each groove, and the cables are attached to the slave discs and the master disc at a single point. Advantageously, the cables can be Bowden cables that can be supported by support plates attached to the entry points of the slave discs and the master disc. For optimized steering geometry based on the Ackermann principle, the circumferential grooves of the slave discs can optionally be provided with a cam track, thereby optimizing the steering geometry depending on the wheelbase and track width of the bicycle.

[0013] A lever system can be attached to at least two crossbeams connected by hinges. The lever system can include a locking pin which, via an actuating mechanism, can be extended into an opening in the lever system to block the rotational movements of the crossbeams and re-inserted to release the blockage.

[0014] This prevents the bicycle from tipping over, which is particularly advantageous when parking the bicycle, as a secure stand can be achieved without the need for additional elements such as a stand for stabilization.

[0015] The actuating mechanism for the locking pin may include a further cable pull which can be actuated by the handlebar, for example with a lever, in particular with a lockable lever.

[0016] The inventive design can be used as an add-on solution (and is reversible), does not require a separate, specially designed frame, and does not function as a turntable. Instead, it utilizes a double-fork design with two conventional front forks, which are pivotally connected to each other in two planes via parallel, mounted cross members. The tilting of the bicycle around the tilt angle κ is thus enabled by the parallelogram formed by the cross members. This tilting angle κ can be transmitted via movable cross members from a centrally located head tube extension, which can be rigidly connected to the head tube of the bicycle frame and non-rotatably by suitable means, to the two parallel front forks.

[0017] Maintaining the frame's head tube angle (β) and the fork offset (Kr) results in the typical bicycle handling characteristics, allowing the bicycle to be used immediately without any familiarization period. Twisting of the multi-track mounting system relative to the frame (around the head tube) can be prevented by bracing, for example, with cables.

[0018] A large steering angle (>70°) can be achieved by transmitting steering movements from the handlebars to the outer slave discs, which are rigidly connected to the secondary steering heads of the forks, via cables. Discs may be used for this purpose. Each of the two slave discs, assigned to one fork, can be actuated by two cables per steering direction, so that if one cable fails (breaks, etc.), the steering remains fully functional.

[0019] A locking mechanism allows the tilting function to be locked, securing the bicycle against tipping over with a lever system and locking pin. This function can be remotely controlled from the handlebars and, in combination with an installed parking brake, can replace a standard bicycle kickstand. Furthermore, stopping (at traffic lights, etc.) is possible without dismounting.

[0020] The invention enables the adaptive conversion of a single-track bicycle to a multi-track bicycle without significantly affecting its handling. The tilting mechanism allows for a natural riding feel. By locking the tilting function of the front wheels, a stable stance can be achieved while maintaining full maneuverability of the bicycle (enabling the integration of autonomous driving functions, etc.).

[0021] The invention enables a combination of applying the tilting parallelogram to a bicycle with different conventional frames, realizing the transmission of steering torques using cables or Bowden cables, and locking the tilting mechanism from the handlebars, using standard bicycle components to the greatest extent possible.

[0022] Furthermore, safe handling is possible with a very short familiarization period, and a return to a single-track bicycle is always possible. The three wheels also provide a greater sense of security. Stopping without dismounting is possible. Additionally, its performance on slippery roads is improved compared to single-track bicycles.

[0023] The invention will be explained in more detail below by way of example.

[0024] This shows: Fig. 1 in schematic front view an essential part of an example of a front axle construction according to the invention in vertical orientation; Fig. 2 the example of Fig. 1 during a curve with a tilt angle k; Fig. 3 a side view of a front wheel area with front axle construction; Fig. 4 a perspective view of an example of a front axle construction according to the invention; Fig. 5 that in Fig. 4 examples shown in a front view and Fig. 6 that in the Fig. 4 and Fig. 5. Example shown in a view obliquely from above.

[0025] With Fig. Figure 1 illustrates that a head tube extension 3, which can be rigidly mounted in or attached to a head tube 17 of a bicycle frame 1, can be connected to two secondary head tubes 2.1 of two forks 2, for two parallel bicycle wheels 4, via two cross members 7. The connection is achieved with pivot joints 6. By means of the pivot joints 6, the cross members 7 with the forks 2 can be pivoted about horizontally aligned axes of rotation by a respective tilt angle k, as shown in Figure 1. Fig. 2 shown and is beneficial when the bicycle is cornering.

[0026] In Fig. Figure 3 shows the attachment of the front axle assembly to the frame 1 via the head tube 17, as well as a suitable means for preventing rotational movement 3.2. In the example shown, four cross members 7 are present, which are connected to the secondary head tubes 2.1 by means of swivel joints 6. Two cross members 7 are positioned in front of and two are positioned behind the head tube extension 3 in the direction of travel, thus achieving a more stable attachment of the entire axle assembly to the frame 1.

[0027] In Fig. Figure 4 shows a particularly suitable method for steering assistance. A slave disc 8 is rigidly attached to each of the secondary steering heads 2.2. A master disc 9 is rigidly attached to the steering tube 3.1. The axes of rotation should each be oriented essentially parallel to the vertical.

[0028] Grooves are formed on the outer surfaces of discs 8 and 9, in each of which a cable—preferably a Bowden cable—is guided. These cable systems 10 to 13 transmit torque during steering from the handlebar 5, via the steering tube 3.1, to the secondary steering heads 2.2 and the forks 2, and ultimately to the wheels 4. The ends of the cables of the cable systems 10 to 13 are attached to the respective slave disc 8 or master disc 9, allowing them to wind or unwind more or less around the respective disc 8 or 9 depending on the angle of the handlebar.

[0029] With the in Fig. Figure 5 of the front view further illustrates that a support plate 15 can be attached to each of the discs 8 and 9, which can serve as a stop for a Bowden cable if cables 10 to 13 are designed as Bowden cables.

[0030] Furthermore, one can Fig. 5 and Fig. As can be seen from Figure 6, two crossbeams 7, which are preferably arranged in the direction of travel in front of the steering tube extension 3, can additionally be connected via a lever system 14. The levers of this lever system 14 can be rigidly connected at their ends to the respective crossbeam 7. The circular openings in both levers of the lifting system 14 are concentrically aligned with each other at a tilt angle of κ=0 and can be fixed with an extendable locking pin 16. The rigid connection of the respective levers of the lever system 14 prevents relative movement of the crossbeams 7 and maintains the tilt angle κ=0.

[0031] A locking pin 16 can be inserted into an opening formed on the lever system 14 to lock the tilting of the bicycle and withdrawn from the opening to release the lock. The movements of the locking pin 16 can advantageously be initiated from the handlebar 5, for example, by a Bowden cable actuated by a preferably lockable lever. The means for moving the locking pin 16 are not shown. 1 frame 2 forks 2.1 secondary head tube 2.2 secondary steering head 3. Head tube extension 3.1 Steering tube 3.2 Means to prevent rotational movement (roping) 4-wheeler 5 handlebars 6 Swivel joint 7 Crossbeam 8 slave discs 9 Sensor disc 10 cable pull 11 Pulley 12 cable pull 13 Pulley 14 lever system 15 Support plate 16 locking pin 17 Head tube

Claims

[1] Front axle construction for a bicycle with two front wheels (4), each of which is rotatably mounted in a fork (2), wherein the two forks (2) are rotatably attached to secondary head tubes (2.1) and a head tube extension (3) by means of at least two cross members (7) arranged in two planes at a distance from one another, and the head tube extension (3) is arranged centrally between the secondary head tubes (2.1), and a steering tube (3.1) is rotatably mounted within the head tube extension (3) and the steering tube (3.1) can be connected to a handlebar (5), wherein Swivel joints (6) on the head tube extension (3) and the secondary head tubes (2.1) are arranged in two parallel planes and the planes are arranged parallel to the horizontal, characterized by , that the head tube extension (3) can be guided through a head tube (17) of a frame (1) and is rigidly mounted therein or can be rigidly connected to the head tube (17) and a slave disc (8) is rigidly attached to the secondary steering heads (2.2) rotatably connected to the respective fork (2) and a master disc (9) is rigidly attached to the steering tube (3.1) rotatably about a vertically aligned axis and at least one groove running around the radially outer surface is formed on the slave disks (8) and at least two grooves running around the radially outer surface and aligned parallel to one another are formed on the master disk (9), at least one cable (10, 11) being guided in each of the grooves and the cables (10, 11) being fastened at one position on the slave disks (8) and on the master disk (9). [2] Front axle construction according to claim 1, characterized bythat a total of four cross members (7) are rotatably connected to the head tube extension (3) and the secondary head tubes (2.1), wherein a pair of the cross members (7) are arranged in front of the head tube extension (3) in the direction of travel and a pair of the cross members are arranged in the direction of travel after the head tube extension (3). [3] Front axle construction according to one of the preceding claims, characterized by that additional cables (12, 13) are guided between the slave discs (8) and in the slave discs (8) in additional grooves and are fastened to the slave discs (8). [4] Front axle construction according to one of the preceding claims, characterized by that the cables (10, 11, 12, 13) are guided through support plates (15) fixed to the slave disks (8) and the master disk (9) and the cables are designed as Bowden cables which are supported on the support plates. [5] Front axle construction according to one of the preceding claims, characterized bythat a lever system (14) is fastened to the at least two cross members (7) which are connected to one another in an articulated manner, and a locking pin (16) is provided on the lever system (14), which locking pin can be guided into an opening for blocking the rotary movements of the cross members (7) and out for releasing the blocking by means of an actuating mechanism. [6] Front axle construction according to the preceding claim, characterized by that the actuating mechanism has a further cable which can be actuated by the handlebar (5).

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