BACKGROUND ART Front wheel suspensions are usually realised by a telescopic front fork. In such a relatively simple solution7 the telescopic front fork has a triple function: namely, the pair of parallel pipes sliding within each other must provide for wheel track guidance as well as springing since springs, com- bined with shock absorbers, are usually placed in the telescopes; and thirdly, it must also provide for taking up forces during breaking. Practical experience has proved that these contrary requirements cannot be ade- quately complied with by applying traditional telescopic-fork front wheel suspensions.

So, one function of a front wheel suspension is the accurate guidance and steering of the wheel, for which high bending and torsional stiffness are required, otherwise the telescopic pipes will get wedged in. On the other hand, it produces a considerable load to take up brake outrigging force during breaking since its horizontal component acts towards wedging in the telescopic pipes sliding on each other. The above requirements could only be satisfied by applying very massive telescopic pipes with large di- ameter, but their internal friction is too high, therefore a great amount of force is needed to move them; consequently they do not spring smoothly enough, so the connection between the wheel and the road surface is deteriorated. These problems are aggravated by the fact that a motorbike

,,kneels down" during breaking, meaning that the telescopic pipes slide into each other as a result of a sudden compressive force, therefore springing is practically suppressed in this said state which is critical any- way.

There is a front wheel suspension known as ,,TELELEVER", developed by the German BMW Company (its detailed description can be found e.g. in Volume 6/1993 of a Hungarian special periodical titled "MOTOR REVIEW"). This front wheel suspension comprises a guiding telescopic front fork, a longitudinal triangular mounting unit, and a central spring leg.

There are other front wheel suspensions known as "PAIOLI" and "GILERA", respectively, as well, (described in Volumes 1/1991 and 8/1991, respectively, of the same special periodical "MOTOR REVIEW") and operating on basically the same principle. Here a forked unit compris- ing a fork and a fork shank is applied, in which a steered wheel is rota- tively embedded. The fork shank is cased by a shell allowing for only a relative axial displacement. A springing mechanism comprising a single spring element and combined with a shock absorber is mounted between the telescopic shell and the fork shank. A steering control shaft of a steering device, which former can be rotated together with a control horn, is connected to a motor-cycle chassis through a connecting unit in such a way that the steering device can be only rotated around the steering con- trol shaft, relatively to the motor-cycle chassis. The steering device com- prises a mechanism transmitting the steering rotation of the shell to the forked unit.

A deficiency of the latter solution is that since the forked unit is not con- nected to the chassis at the bottom and since the fork shank is embedded in the shell by bearings with a relatively small spacing, the bearings with a

small spacing placed in the relatively small shell are loaded along a rela- tively large arm of force coming from the wheel. Therefore there is a con- siderable danger of wedging in. Another problem, already referred to above, is that such a front wheel suspension does not solve the problem of transmitting forces produced during breaking to the motor-cycle chas- sis. As opposed to traditional telescopic fork solutions, the only advan- tages of this reversed and single-telescope solution are that it has a rela- tively simple structure and comprises only one sliding element.

The triple requirement mentioned above has not been managed to be en- tirely completed by either of the two solutions detailed above DISCLOSURE OF THE INVENTION An object of the present invention is to eliminate the deficiencies above, that is, to produce an improved front wheel suspension that would solve the complex problem of wheel guidance, springing, and breaking force take-up by structurally dividing these functions. Another object of the pre- sent invention is to provide a solution which is structurally simple, can be manufactured economically, and satisfies aesthetical demands,too.

The object has been solved by further developing the front wheel sus- pension described in the introduction in accordance with the present in- vention, comprising an additional radius rod mounted between a motor- cycle chassis and a forked unit, which is hinged to the motor-cycle chas- sis, and connected to the forked unit through a first connecting unit allow- ing for a rotation around a steering centre line, as well as for a change in a relative angular position ( angle a) of the steering centre line and the radius rod during springing. Furthermore, besides providing for the ro- tatability of the steering device, a second connecting unit mounted be-

tween the steering device and the motor-cycle chassis also allows for a change in a relative angular position ( angle ) of the steering centre line and the motor-cycle chassis during springing.

In a practical embodiment of the present invention, the forked unit pref- erably has a single-arm fork, and the first connecting unit mounted be- tween the radius rod and the forked unit is a ball-and-socket joint. This way a very simple structural design can be carried out.

The springing mechanism is preferably mounted outside a shell, between the radius rod and the motor-cycle chassis, and is practically a single springing element combined with a shock absorber.

In an other embodiment of the present invention, the second (upper) con- necting unit comprises a ball-and-socket joint, through which the motor- cycle chassis and the shell jointly rotatable with a control horn are directly connected to each other.

In a further, particularly preferable embodiment of the present invention both connecting units are ball-and-socket joints or universal joints.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be described in more detail with reference to the accompanying drawings where some examples for embodiments of the solution in accordance with the present invention are shown. In the drawings:

- Figure 1 illustrates a side view of a first embodiment of a front wheel suspension in accordance with the present in- vention; - Figure 2 illustrates a semi-sectional view along line ll-ll in Figure 1; - Figure 3 illustrates a section along line Ill-Ill in Figure 1; - Figure 4 illustrates a partially sectional side view of a second embodiment of the solution in accordance with the pre- sent invention; - Figure 5 illustrates a semi-sectional view along line V-V in Fig- ure 4; - Figure 6 illustrates a partially sectional front view along arrow VI on Figure 4; - Figure 7 illustrates a partially sectional side view of a third em- bodiment of the solution in accordance with the present invention; - Figure 8 illustrates a section along line VIII-VIII in Figure 7; - Figure 9 illustrates a partially sectional side view of a fourth embodiment of the solution in accordance with the pre- sent invention.

Similar details on the drawings have been indicated by identical reference numbers.

DETAILED DESCRIPTION OF THE DRAWINGS Figure 1 illustrates a side view of a front part of a motor-cycle, with par- ticular regard to a front wheel suspension in accordance with the present invention. This motor-cycle has a motor-cycle chassis 1 and a steered front wheel 2, embedded rotatively in a forked unit 3 . The forked unit 3

comprises a fork 4 and a fork shank 5, which latter is a cylindrical trunnion cap, and, in the present case, the fork 4 and the fork shank 5 constitute a single part. The upper end of the fork shank 5 is supported by a shell 6, exclusively allowing for an axial mutual displacement.

The motor-cycle has a steering device 7, comprising a control horn 8 and a steering control shaft 9, which, in the present case, can be rotated to- gether. The steering rotation of the steering device 7 is transmitted by a mechanism 10 to the forked unit 3 in the present case, comprising a plu- rality of hinged arms known in themselves.

In accordance with the present invention, there is a radius rod 11 (swinging lever) mounted between the motor-cycle chassis 1 and the forked unit 3; it is hinged to the motor-cycle chassis 1, in the present case through a hinge 12, and is connected to the forked unit 3 through a first (lower) connecting unit 13. This connecting unit 13, on the one hand, al- lows the forked unit 3 to be rotated around a centre line of the fork shank 5, and on the other hand, it allows for a change in a relative angular posi- tion of the centre line of the fork shank 5 parallel to a steering centre line 30 and the radius rod 11 during springing. The alternating angle between the radius rod 11 and the centre line of the fork shank 5 is indicated by II,,I There is a second (upper) connecting unit 14 mounted between the steering device 7 and the motor-cycle chassis 1 which provides for ro- tatability around the steering centre line 30, on the one hand, and also allows for a change in a relative angular position of the steering centre line 30 and the motor-cycle chassis 1 during springing, on the other hand, <BR> <BR> <BR> <BR> in accordance with the present invention; said angle is indicated by "in Figure 1.

It can be well observed in Figure 1 that the motor-cycle is equipped with a springing mechanism 15, mounted between the motor-cycle chassis 1 and the radius rod 11 in accordance with the present invention, that is, it is connected to the motorcycle chassis 1 by a hinge 16, and to the radius rod 11 by a hinge 17 placed in its central area. The springing mechanism 15 is combined with a shock absorber (not shown) in a way known in it- self.

Figures 2 and 3, respectively, illustrate the details of the solution shown in Figure 1 in a relatively larger scale and in a partially sectional view. The details of the lower connecting unit 13 and of the upper connecting unit 14 are distinctly visible in Figure 2. On the lower part of Figure 2, it can be seen that a part of the fork shank 5 being immediately above the fork 4 which is a cylindrical trunnion cap as mentioned above, is embedded in a hub 20 by a plurality of bearings 18 and 19. This hub 20 is provided with a pin 21 on each side, respectively. In the present case, each of these pins 21 is embedded in a bearing 22. Said bearings 22 are placed in the front shanks of the radius rod 11, which in the present case, is H-shaped. From this arrangement it follows that the hub 20 is rotatively mounted relatively to the fork shank 5, and the shanks on both sides of the radius rod 11 can be relatively rotated on the pins 21 in accordance with springing dis- placements (in angle a; see Figure 1).

The upper part of Figure 2 illustrates the way in which the upper end of the fork shank 5 is embedded in the shell 6. It has already been men- tioned above that the fork shank 5 can be relatively shifted in relation to the shell 6. The upper end position of the shell 6 is limited by a stop 23, which, in the present case, is screwed onto the upper end of the fork shank 5. Forming a part of the upper connecting unit 14, the shell 6 is

provided with a pin 24 on each side, each of which is embedded in the motor-cycle chassis 1 by a bearing 25. There is a ring 28 connected to the lower part of the (telescope-like) shell 6 by bearings 26 and 27 in a rela- tively rotatable fashion. Said ring 28 is linked to the upper ends of the re- spective hinged arms of the above-mentioned hinged mechanism 10 transmitting the steering displacement. The lower ends of the hinged arms on both sides of hinged mechanism 10 are coupled to the fork shank 5 by a pin 29, respectively (see Figures 1 and 2).

Figure 3 illustrates the arrangement and the embedding of the steering device 7 in more detail. The control horn 8 is fixed onto the steering con- trol shaft 9 in a way known in itself, the centre line of which is identical with the steering centre line 30. The steering control shaft 9 is embedded rotatively in a steering box 33 by bearings 31 and 32. The steering box 33, however, is mounted rotatively by pins 34 and 35, in accordance with the present invention, which latter are perpendicular to the steering centre line 30 in relation to the motor-cycle chassis 1. This way a small amount of tilting displacement is provided during springing meanwhile the value of angle Q is altered (see Figure 1).

There is a crossbar 36 mounted on the lower end of the steering control shaft 9. On both ends of said crossbar 36 a plurality of ball-and-socket joints 38 have been applied in order to connect a plurality of transmission bars 37 (see Figure 1) in order to transmit the steering movement. Only one of the transmission bars 37 can be seen in a side view in Figure 1; the back end of said transmission bar 37 is connected to the ball-and- socket joint 38 of the crossbar 36, and its front end to a ball-and-socket joint 39. The two ball-and-socket joints 39 are arranged opposite to each other on the ring 28 (see Figure 2).

Consequently, in the case of a motor-cycle equipped with a front wheel suspension as shown in Figures 1-3, the fork shank 5 slides longitudinally in the shell 6 when the wheel 2 is sprung in the course of being moved, while the value of the angle a between the fork 4 and the radius rod 11 is slightly changed. Nevertheless, this angle alteration is made possible by the front wheel suspension in accordance with the present invention as the radius rod 11 can be freely rotated on the pins 21 of the hub 20; fur- thermore, the motorcycle chassis 1 can be relatively displaced accord- ingly on the side pins 24 of the shell 6, that is, angle can be slightly al- tered as well. Although this angle alteration is also transmitted to the steering device 7 through the transmission bars 37, practical experience has proved that it is so small that no inconvenience can be caused to a motor-cycle rider.

During steering, the ring 28 is pushed by one of the transmission bars 37 of the steering device 7, and pulled by the other transmission bar 37; said ring 28 can be freely rotated on the shell 6 in accordance with the steering rotation. The ball-and-socket joints 38 and 39 can transmit this steering movement reliably in spite of a series of multi-axis displacements. The rotation of the ring 28 is transmitted to the fork shank 5 by the hinged mechanism 10, which also turns the fork 4 and thus the wheel 2 by rotat- ing freely within the shell 6 and the hub 20. The shell 6 can be provided with a protective housing 40, indicated by a thin dash-and-dot line in Fig- ure 1, the task of which is to prevent pollutants from getting in.

In order to decrease the tilting mass of the shell 6 and the fork 4, they are made as hollow castings of aluminium alloy in the present case. The fork shank 5, in the present case, is a thin-walled pipe made of high-solidity steel alloys. The arms of the hinged mechanism 10 can practically be made of an aluminium alloy with high torsional stiffness, so it is practical

to manufacture them with as much width as possible in order to improve their torsional stiffness.

Figures 4-6 illustrate a second embodiment of the front wheel suspension in accordance with the present invention. This embodiment differs from the embodiment shown in Figures 1-3 in that in the latter the centre line of the fork shank 5 is parallel to the steering centre line 30 , but there is a spacing between them (in the direction of progress of the motor-cycle), whereas in the case of this one the longitudinal centre line of the fork shank 5 falls in the same line with the steering centre line 30 of the steer- ing device 7. Another difference lies is that here a single-arm fork shank 5 is applied (see Figure 6), which is connected to a radius rod 11 through a lower connecting unit 13 comprising a 41 ball-and-socket joint and allow- ing for multi-axis free displacement. Using this single-arm fork 4, the swinging mass has been decreased, one the one hand, and the structure has been considerably simplified by this connecting unit 13, on the other hand.

In Figures 4 and 5 it can be clearly observed that here the control horn 8 of the steering device 7 is directly mounted to a shell 42 (that is, the steering control shaft has been eliminated), which is embedded rotatively on the external mantle of the shell 6 by bearings 43 and 44. The shell 42 is provided with a pin 45 on each side, to which the arms of the hinged mechanism 10 are hinged as described above, thus transmitting the steering displacement. Figures 4 and 5 also illustrate that the lower part of the shell 6 is provided with an extension 46 backwards. The extension 46 is provided with a pin 47 on each side, respectively, which are embedded in a nest 49 of the motor-cycle chassis 1 through a bearing 48, respec- tively. During springing, the steering device 7 and the forked unit 3 can be

displaced together around the pins 47 relatively to the motor-cycle chas- sis 1 in a manner that the angle is altered (see Figure 4).

When the steering device 7 is rotated, the displacement of the shell 42 is transmitted to the single-arm fork 4 by the hinged mechanism 10, there- fore the single-arm fork 4 can be freely rotated in the ball-and-socket joint 41 of the first (lower) connecting unit 13 and the fork shank 5 can also be freely rotated in the shell 6 in accordance with the degree of rotation of the wheel 2. At the times of springing in and out, respectively, the ball- and-socket joint 41 allows for the degree of change necessary in the value of the angle a determining the relative angle position of the centre line of the fork 4 and the radius rod 11. Furthermore, the forked unit 3 can be relatively displaced in relation to the motor-cycle chassis 1 around the pins 47 of the extension 46 of the shell 6, so the value of the angle can change at such instances. It should be noted that in the case of this em- bodiment, the radius rod 11 is Y-shaped, the central front part of which is connected to the ball-and socket joint 11 in a nest-like manner, and its fork-like expanding shanks projecting backwards are connected to the motor-cycle chassis 1 through the hinges 12 on both sides.

Figures 7 and 8 illustrate a third embodiment of the front wheel suspen- sion in accordance with the present invention, which is basically a version of the solution shown in Figures 4-6. Here a radius rod 11 is connected to a single-arm fork 4 in the same way as discussed above, by a first con- necting unit 13 comprising a ball-and-socket joint 41. The difference, however, lies in the embedding and the motion transmission of the steer- ing device 7. Here, the steering device 7 is provided with a steering con- trol shaft 9, embedded in an extension 46 of the shell 6 itself, as shown in Figure 8. Figure 7 illustrates that a longitudinal centre line 5A of the fork shank 5 does not coincide with the steering centre line 30, instead, they

are arranged parallelly to each other with a spacing, the one behind the other in the direction of progress of the motor-cycle.

Figure 8 illustrates in more detail that the steering control shaft 9 is rota- tively embedded in the extension 46 of the shell 6 by a plurality of bear- ings 50 and 51, respectively. In this case, the extension 46 is a shell pro- vided with a pin 52 on each side, respectively, each of which is embedded in the motor-cycle chassis 1 by a bearing 53 (similarly to the solution shown in Figure 1 in the case of the pins 24).

A further difference is represented by the fact that in this embodiment, a carrier rod 54 is connected to the lower end of the steering control shaft 9 in a jointly rotatable fashion. At each end of the carrier rod 54 is mounted a pin 55, through each of which a transmission bar 57 is connected, re- spectively, in order to transmit steering displacements. The front ends of the transmission bars 57 are hinged to a ring 58 which latter is supported by bearings mounted on the shell 6. Since in the case of this embodiment, the steering control shaft 9 is arranged in the extension 46 of the shell 6, it becomes unnecessary to apply ball-and-socket joints at the ends of the transmission bars 57, that is, simple hinges are suitable enough. There- fore the structure can be further simplified.

As a result of the above, it follows that in this embodiment the angle a can also be altered during springing by the first (lower) connecting unit 13 provided with a ball-and-socket joint; and similarly, the change of the an- gle during springing is provided by the second (upper) connecting unit 14; and separately from the aforesaid, steering displacements can be un- disturbedly transmitted to the wheel 2.

In the embodiment shown in Figure 7, a particular suspension for the springing mechanism 15 is outlined. In this case, the lower end of the springing mechanism 15 is not connected directly to the radius rod 11, but by way of a rocking lever 59. In Figure 7, the left end of the rocking lever 59 is connected to the lower end of the springing mechanism 15; the cen- tral part of the rocking lever 59 is hinged to the radius rod 11 by a con- necting rod 60; and the right end of the rocking lever 59 is hinged to the motor-cycle chassis 1. This rocking lever solution makes the characteris- tics of the springing even more progressive, that is, the springing ,,is hard- ened" in the case of heavy spring loads.

Finally, Figure 9 illustrates a fourth embodiment of the front-wheel sus- pension in accordance with the present invention, which constitutes an even further simplified version of the solution shown in Figure 7. In this case, the lower connecting unit13 differs from the design shown in Figure 7 in that here the single-arm fork 4 is provided with an extension 61 back- wards, and the ball-and-socket joint 41, embedded from below by the relative nest of the radius rod 11, of the lower connecting unit 13 is pro- jected downwards from said extension 61. A further discrepancy lies in that the lower end of the springing mechanism 15 is connected directly to the radius rod 11.

In the arrangement shown in Figure 9, the structure and the arrangement of the second (upper) connecting unit 14 has been further simplified. In this case the extension 46 of the shell 6 is directly connected to the motor- cycle chassis 1 through a ball-and-socket joint 62 of the connecting unit 14. The control horn 8 of the steering device 7 is directly mounted on the extension 46 of the shell 6 here and the hinged arms of the hinged mechanism 10 transmitting the steering motion are also hinged to the lower part of the extension 46.

The embodiment illustrated by Figure 9 has the simplest structure possi- ble, but is still capable to comply with the complex requirements described in the introduction. Since the shell 6 is connected to the motor-cycle chassis 1 by the second connecting unit 14 comprising the ball-and- socket joint 62, there is a single structural element, namely, the ball-and- socket joint 62, which ensures that the shell 6 also be able to follow the fork angle changes of the single-arm fork 4 during springing, that is, the alterations in the angle ; on the other hand, it provides for the good steerability of the wheel 2, and at the same time, the ball-and-socket joint 41 of the first (lower) connecting unit 13 accordingly provides for the angle a alterations during springing.

The embodiment illustrated in Figure 9 also differs from the solution shown in Figure 7 in that during steering the single-arm fork 4 and the fork shank 5 do not rotate in the shell 6, because they can be rotated together.

Therefore, in the case of this arrangement, the steering centre line 30 crosses the centre of the ball-and-socket joints 41 and 62, respectively.

In certain cases, of course, double-shank forks instead of the single-arm fork can also be applied for this embodiment and for the corresponding further two embodiments as well.

On the basis whereof it can be established that the front wheel suspen- sion in accordance with the present invention makes it possible to dis- tribute the triple function described in the introduction, namely: wheel track guidance, that is, steering, springing, and brake force take-up, to structural elements basically independent from each other. In our judge- ment, it has been managed for the first time to complete these complex requirements in this way. A further advantage of the solution in accor-

dance with the present invention is that all this is made possible by a rela- tively simple structural design and production.The embodiment illustrated in Figure 9 is deemed to be particularly advantageous since this complex requirement is complied with by engaging the least amount of structural elements possible. Springing can remain "active" all the time, that is, at any wheel load, consequently motor-cycle riders can be made comfortable in any mode of operation. In our judgement, the single-arm fork 4 pro- duces a favourable impression aesthetically as well because it conveys the image of a light and surprising structural design.

The most important advantage of applying the second (upper) connecting unit 14 and the first (lower) connecting unit 13 in accordance with the pre- sent invention is that the steering device 7 and the forked unit 3 are sup- ported by the motor-cycle chassis through said units in a manner that the necessary relative displacements are also allowed for, therefore the problems of the telescope getting wedged in, inevitable in the case of ear- lier solutions, have been completely eliminated.

Finally, it should be mentioned that a great number of other embodiments and combinations of the present invention can be realised within the scope of the patent protection applied for. As regards the connecting units 13 and 14, any other structural units, e.g. mechanisms, could be applied besides the embodiments using ball-and-socket joints and universal joints, providing for rotatability and the relative displacement necessary in the direction of the and angles a and . Naturally, the springing mechanism 15 can be installed in the shell 6 as well, and even a torsional spring can be applied for the springing mechanism 15 at the hinged connection of the radius rod 11 and the motor-cycle chassis 1.

In the above disclosure we mentioned only embodiments of the claimed invention for motor-cycle, but it is to be noted that the present invention can be used for bicycles, tricycles or any other vehicles or devices com- prising a wheel.