MOTORCYCLE PROVIDED WITH A STEERING HUB

Abstract: The invention provides a motorcycle (50) with hub steering, the axle (2) of the hub (1) being fixedly connected to first support arms (56) and being disposed in such a manner that it can turn with respect to the hub body (3). Second support arms (55) are arranged in such a manner that the front pivot points (60, 61) and rear pivot points (62, 63) lie on non-parallel lines (A, C). Attaching the front wheel (52) in this way results in an improved suspension and increased stability of a motorcycle (50) with hub steering.

Description: Motorcycle provided with a steering hub The invention relates to a motorcycle with what is known as hub steering, and in particular to a front wheel suspension for a motorcycle of this nature. In standard motorcycles, the steering wheel, which is generally the front wheel, is held in a front fork with the aid of its hub and axle. The wheel can turn due to the fact that the front fork as a whole is arranged so that it can rotate with respect to the frame of the motorcycle. The hub merely allows the wheel to rotate about its axle. Designs are also known in which the wheel can turn with respect to its axle. An example of such designs is shown in French patent 1,000,493. In this known design, the (driven) axle is accommodated in the hub by means of a cardan structure. The wheel, which obviously moves together with the hub, is able to turn freely with respect to the axle. The wheel is steered by means of a steering arm, which is preferably arranged resiliently. This known design has various drawbacks. Firstly, the cardan suspension is not free from vibration. Secondly, the imaginary line about which the wheel is rotated during steering passes straight through the axle, resulting in unsatisfactory motorcycle driving characteristics. In particular, the stability will be inadequate. American patent US 5,042,609 describes a motorcycle with a turnable hub, the turning axis of the handlebars intersecting the wheel axle. The hub is connected to the frame of the motorcycle by means of a single support arm. European patent EP 0,432,107 likewise describes a motorcycle with a pivotable hub. This hub, the axle of which is fixedly connected to the frame of the motorcycle, allows the wheel, which is arranged so that it can rotate about the hub, to turn. In connection with this hub, the said patent notes that the axle may be arranged in front of the turning axis of the handlebars, in such a manner that the axis of rotation of the wheel and the turning axis of the handlebars do not intersect one another. This known hub is connected to the frame of the motorcycle by means of a single pair of support arms . A steering rod connects the turnable part of the hub to the handlebars . A structure of this nature, with a single pair of support arms, has the drawback of being relatively unstable. The support arms can become twisted relatively easily under the influence of transverse forces, and this affects the position of the front wheel and therefore the stability of the motorcycle. The object of the invention is to eliminate the above and other drawbacks of the prior art and to provide a motorcycle which allows what is known as hub steering with considerably improved driving characteristics. Furthermore, the invention aims to provide a motorcycle with improved stability. To this end, the invention provides a motorcycle, comprising a frame, a front wheel, a rear wheel and an engine, the front wheel being provided with a hub with an axle, which is fixedly connected to a first set of support arms, and a hub body which is arranged around the axle and is connected to the axle in such a manner that it can turn about a turning axis which is substantially perpendicular to the longitudinal direction of the axle, and the first set of support arms being pivotably connected to the frame, characterized in that the axle is held fixedly in connecting pieces, the first support arms each being connected to a connecting piece via first front pivot points and to the frame via first rear pivot points, in that second support arms are each connected to a connecting piece via second front pivot points and to the frame via second rear pivot points, which pivot points, in operation, allow a movement in a substantially vertical plane, and in that the line which joins the front pivot points and the line which joins the rear pivot points intersect one another at a point which lies above the support arms. By providing a set of second support arms, preferably above and approximately parallel to the first support arms, it is possible to achieve greater stability of the motorcycle. Designing the support arms in such a manner that the pivot points do not lie on parallel lines, but rather on intersecting lines, results in a highly advantageous steering sensitivity during compression. It should be noted that the invention is not limited to motorcycles. Although the invention is explained, by way of example, on the basis of a motorcycle, the term motorcycle may also be understood to mean bicycle, moped or, for example, a three-wheeled vehicle, with or without engine motor. The invention will be explained in more detail below with reference to the drawing, in which: Fig. 1 shows a perspective view of a hub with part of the front suspension according to the invention. Fig. 2 shows a view, likewise in perspective, of the hub of Figure 1 in a wheel of a motorcycle . Fig. 3 shows, partially in section, a front wheel of a motorcycle according to the invention. Fig. 4 shows a side view of a motorcycle provided with hub steering according to the invention. The embodiment of a hub 1 according to the invention which is shown in a perspective, partially cutaway view comprises an axle 2 , a hub body 3 and a pivot pin 4. The axle 2 is arranged fixedly, for example by means of a "shrink fit", in a block 5, in which the pivot pin 4 is also held fixedly. The centre axis of the pivot pin (or turning axle) 4 forms the turning axis A of the hub. For this purpose, the pivot pin 4 is connected to the hub body 3 in such a manner that it can turn and that the hub body 3 can turn about the turning axis A. Recesses 8 which serve to accommodate wheel bearings are arranged on the outside of the hub body 3. With the aid of flanges 11, the axle 2 is arranged fixedly in the connecting pieces 57, which are used to connect the hub to the frame (not shown) of the motorcycle. For the sake of clarity of the figure, only one flange 11 is shown. The ends of the axle 2 are preferably each provided with toothing which engages with the (internal) toothing of the corresponding flange 11, thus preventing unintentional rotation. Openings 80 and 81 for holding pivot points (60 and 61 in Fig. 4) are arranged in each of the connecting pieces 57a and 57b. As will be explained in more detail below with reference to Fig. 4, the pivot points 60 and 61 serve to attach the connecting pieces 57 in such a manner that they can pivot with respect to the frame of the motorcycle . The lines which join the centre points of the openings 80 and 81, and therefore of the pivot points 60 and 61, in each of the connecting pieces 57a and 57b are respectively denoted by X and Y in Figs. 1 and 2. The lines X and Y lie (in the load-free state of the motorcycle) in a single plane, together with the line Z which joins the openings 80 in the connecting pieces 57a and 57b. Preferably, the distance D between the turning axis A and the centre axis B of the axle 2 is selected to be such that the turning axis A and the lines X and Y can lie in a single plane. In other words, the lines X, Y and A preferably lie at equal distances from the line B. This results in optimum driving characteristics for the motorcycle equipped with a hub of this nature . Steering brackets 65a and 65b (of which 65b is shown only in part) are arranged on either side of the hub body 3. An opening 69 which is arranged in the steering brackets 65 simplifies assembly of the axle 2 and the hub 1. Fig. 2 shows how the hub 1 of Figure 1 can be held in a wheel 52 of a motorcycle. Wheelbearings 10, around which the wheel 52 is arranged so that it can rotate, are accommodated in the recesses 8 (cf . Figure 1) in the hub body 3. Steering brackets 65a and 65b (of which the bracket 65a is shown only in part for the sake of clarity of the drawing) are fixedly connected to the hub body 3, for example by means of screws (not shown) . The steering brackets 65a and 65b are rigidly connected to one another by means of an intermediate piece 101, with the result that the separate steering brackets 65a and 65b cannot move or rotate with respect to one another. This intermediate piece 101 is pivotably connected, by means of, for example, a ball-and-socket joint 100, to a centring bracket 102 with legs 102a and 102b. This centring bracket 102 is attached pivotably (cf. also Fig. 4), by means of the two bracket legs 102a, 102b, to the frame 51 of the motorcycle, as will be explained in more detail below with reference to Fig. 4. This centring bracket 102 prevents any displacement of the steering brackets 65a and 65b, at the location of the intermediate piece 101, parallel to the axle 2. This results in improved steering characteristics for the motorcycle 50. Connecting pieces 71 connect the steering brackets 65 to handlebars (cf. Figure 4). These connecting pieces are attached in such a manner that they can pivot both with respect to one another and with respect to the steering brackets 65, in order to allow a resilient movement of the wheel 52 with respect to the frame 51. Furthermore, the steering brackets 65a and 65b, at the location of the pivoting attachment to the bottom con- necting pieces 71, are connected to one another by a sleeve 73 , in order to be able to transmit the steering movement of handlebars 70 (cf. Fig. 4) to the steering brackets 65a, 65b and the hub body 3 which is attached thereto. As can be seen from Figure 2, the wheel 52, around which a tyre 58 is arranged, can turn about the turning axis A of the hub 1. Fig. 3 shows a steering hub in its position in which it is installed in the front suspension of a motorcycle according to the invention, the figure showing a cross section in a horizontal plane on line B of Fig. 1, i.e. the centre axis of the axle 2. Like Fig. 1, Fig. 3 shows the hub 1, the axle 2 of which is held fixedly, i.e. non-rotatably, in the block 5. The block 5 is arranged fixedly around the pivot pin 4, which for its part is arranged so that it can turn in the hub body 3. It should be noted that the centre axis A of the pivot pin 4 (cf . Fig. 1) is preferably not perpendicular to the plane of the drawing, but rather forms an angle of, for example, 65° with this plane. Wheel bearings 10 are arranged on the hub body 3 in such a manner that the wheel 52 can rotate about the hub body 3 (cf . Fig. 2) . A tyre 58 is arranged on the wheel 52. The axle 2 of the hub 1 is fixedly connected to the connecting pieces 57a and 57b, which for their part are fixedly connected to the (first) support arms 56a and 56b. As can be seen from Fig. 3, the arms 56a and 56b form a single unit in the embodiment illustrated. The assembly comprising the arms 56a and 56b is (preferably pivotably) connected to the frame of the motorcycle, as will be explained in more detail below with reference to Fig. 4. In order to be able to steer the hub 1, and therefore the wheel 52, steering brackets 65a and 65b are provided, which are fixedly connected to the hub body 3 on either side of the latter (cf. Figs. 1 and 2), either directly or indirectly via one or more brake calliper attachment (s) (not shown) . In order to be able to attach and remove the wheel 52 easily, the brake calliper attachment is preferably attached firstly to the hub body 3 before the steering bracket is attached thereto. The steering brackets 65a and 65b are preferably resiliently connected to the handlebars of the motorcycle, as will be explained in more detail below with reference to Figure 4. As can be seen from Fig. 3, the centre axis A of the pivot pin 4 is situated at a certain distance (denoted in Fig. 3 by D) from the centre axis B of the axle 2. The fact that the turning axis A of the wheel 52 therefore does not intersect the centre axis B of the axle results in improved stability of the motorcycle . Fig. 4 shows a side view, by way of example, of a part of a motorcycle 50 according to the invention. The rear part of the motorcycle 50 may be constructed in a customary manner, for example in accordance with European patent EP 0,432,107. The motorcycle 50 illustrated comprises a frame 51 and an engine 54 which is accommodated therein. A hub according to the invention, which is fixedly connected to the connecting piece 57 by means of a bolt, for example, is accommodated in the wheel 52. The connecting pieces 57 are connected to the frame 51 by means of first arms 56 and second arms 55 (only the left-hand arms being shown in Fig. 4; cf . also Fig. 3) . The first arms 56 are connected by means of the pivot points 61 and 63, respectively, to the connecting pieces 57 and frame 51, while the second arms 55 are connected by means of the pivot points 60 and 62, respectively, to the connecting pieces 57 and the frame 51. A support 59 and a rod 72, which is pivotably connected thereto, provide the coupling between the first support arm 56 and a suspension mechanism. The pivot points 62 and 63 are connected to the frame by means of adjustable eccentrics 91 and 92. A steering bracket 65 is connected to the hub, as illustrated in more detail in Figures 2 and 3. In this embodiment, pivotably arranged connecting pieces 71 connect the steering brackets 65 to the handlebars 70, resulting in a resilient steering connection between the handlebars 70 and the wheel 52. In Fig. 4, the connecting pieces 71 are illustrated to the left of the central pivot in the plane of the drawing, but may also be arranged on the right. The latter embodiment is preferred, in order to achieve improved steering characteristics. Other forms of coupling between the steering brackets 65 and the handlebars 70 are also possible. An intermediate piece 101, which is pivotably connected to the centring bracket 102 (cf . also Fig. 2) is also positioned on the steering brackets 65a and 65b. By means of pivots 105 (on both sides of the frame 51) , the legs 102a and 102b of the centring bracket 102 are pivotably connected to auxiliary rods 103, which are also pivotably attached to the frame 51 with the aid of pivots 104. The fork-like shape of the centring bracket 102 (cf. Fig. 2) prevents displacement of the steering brackets 65a and 65b parallel to the axle 2, and does not limit the resilient movement of the wheel 52 and the steering brackets 65a, 65b attached thereto. As can be seen from Fig. 4, the line X which joins the pivot points 60 and 61 is situated at a distance D' from the centre axis (B in Figs. 1, 2 and 3) in the embodiment illustrated. As can be seen from Fig. 2, this distance D' corresponds to the distance D between the turning axis (centre axis of the pivot pin 4) A and the centre axis B of the axle 2. Moreover, in the embodiment illustrated, the orientation of the lines A and X is identical. As a result, the turning axis (A in Fig. 1) will lie in the same plane as the line X which joins the front pivot points 60 and 61. The result is an optimum trailing effect N. As illustrated in Fig. 4, the trailing effect N is equal to the distance between the point at which the wheel is in contact with the ground and the point at which the turning axis (positioned in a common plane with the lines X and Y) intersects the ground. It will be clear that the trialing effect can be varied by varying the distance D or D' . Although it is preferable for the distances D (Figs. 1 and 3) and D' (Fig. 4) to be equal, this is not imperative . The abovementioned orientation of the lines X and A partly determines the driving characteristics of the motorcycle 50. In the embodiment illustrated, the angle between the lines X and A, on the one hand, and the horizontal plane (the ground) , on the other hand, is approx. 65°. In principle, angles of between approx. 45° and 90° are possible, preferably between 60° and 70°. Although the lines X and A preferably have identical orientations (angles with respect to the horizontal plane) , this is not essential and they may be at different angles from one another. As can be seen from Fig. 4, the line C which joins the rear pivot points 62 and 63 does not run parallel to the lines A and X. In the embodiment illustrated, the lines A and C include an angle a which is approximately 35°. According to the invention, the angle a is greater than zero. The angle preferably lies between 10° and 60°, in particular between 30° and 40°. The adjustable eccentrics 91 and 92 can be used to change the orientation of the line C, and therefore the angle α. Incidentally, in the motorcycle according to the invention, the first and second support arms 56 and 55 are not entirely parallel, but rather include an angle of, for example, 10°, as shown in Fig. 4. A mudguard is not shown for the sake of clarity of the drawing. However, a mudguard can easily be connected to the steering brackets in order to provide a good protective action. In a particular embodiment of the steering bracket, the mudguard is formed integrally with the steering bracket. As a result, there is no need for any additional attachment means . It will be clear to the person skilled in the art that the invention is not limited to the embodiments illustrated and that numerous amendments and additions are possible without departing from the scope of the invention.

Claims: CLAIMS 1. Motorcycle (50), comprising a frame (51), a front wheel (52) , a rear wheel (53) and an engine (54) , the front wheel (52) being provided with a hub (1) with an axle (2) , which is fixedly connected to a first set of support arms (56) , and a hub body (3) which is arranged around the axle (2) and is connected to the axle (2) in such a manner that it can turn about a turning axis (A) which is substantially perpendicular to the longitudinal direction of the axle (2) , and the first set of support arms (56) being pivotably connected to the frame (51) , characterized in that the axle (2) is held fixedly in connecting pieces (57) , the first support arms (56) each being connected to a connecting piece (57) via first front pivot points (61) and to the frame (51) via first rear pivot points (63) , in that second support arms (55) are each connected to a connecting piece (57) via second front pivot points (60) and to the frame via second rear pivot points (62) , which pivot points (60, 61, 62, 63), in operation, allow a movement in a substantially vertical plane, and in that the line (A) which joins the front pivot points (60, 61) and the line (C) which joins the rear pivot points (62, 63) intersect one another at a point which lies above the support arms (55, 56) . 2. Motorcycle according to claim 1, in which the said lines (A, C) include an angle of from 30 to 40°. 3. Motorcycle according to claim 1 or 2 , in which the front pivot points (60, 61) present in the connecting pieces (57) lie in the same plane as the turning axis (A) of the hub (1) . 4. Motorcycle according to one of the preceding claims, in which the first arms (56a, 57b) form a single unit . 5. Motorcycle according to one of the preceding claims, in which the turning axis (A) and the centre axis (B) of the axle (2) are situated at a distance (D' ) from one another . 6. Motorcycle according to claim 4, in which the distance (D) between the turning axis (A) and the centre axis (B) of the axle (2) is between 3 and 5 cm. 7. Motorcycle according to claim 5 or 6 , in which the axle (2) of the hub (1) is arranged at a distance (D' ) from the line (A, X) which joins the front pivot points (60, 61) , which distance is preferably equal to the distance between the turning axis (A) and the centre axis (B) of the axle (2) . 8. Motorcycle according to one of the preceding claims, in which the hub body (3) is composed of two substantially symmetrical parts. 9. Motorcycle according to one of the preceding claims, in which the hub (1) is provided with recesses (8) for accommodating wheel bearings (10) . 10. Motorcycle according to one of the preceding claims, in which the axle (2) is arranged at a distance from the two front pivot points (60, 61) . 11. Motorcycle according to one of the preceding claims, in which steering brackets are attached to the hub body (3) for the purpose of turning the hub body (3) with respect to the turning axis (A) . 12. Motorcycle according to one of the preceding claims, in which the steering brackets (65) are rigidly connected to one another by means of at least one inter- mediate piece (101) . 13. Motorcycle according to claim 12, in which the intermediate piece (101) is connected to the frame (51) in such a manner that there is no possibility of displacement parallel to the axle (2) . 14. Motorcycle according to claim 11, in which a mudguard is formed integrally with the steering bracket (65) .

Inventors: VAN DER HEIDE HENDRIK ROELOF, VAN DER HEIDE, HENDRIK, ROELOF
Applicants: HEIDE HENDRIK ROELOF V D, VAN DER HEIDE, HENDRIK, ROELOF
Application year: 1999
Main classification: B62K21
IPC codes: B62K21, B62K25