TECHNICAL FIELD OF THE INVENTION

[ 0001 ] The present invention refers to the technical field of suspensions for transport vehicles and concerns in particular a motorcycle front swing arm suspension.

BACKGROUND OF THE INVENTION

[ 0002 ] In the motorcycle field, it is known that a swing arm suspension is used in the forecarriage of the motorcycle. A swing arm suspension, which may be either a single-sided fork or a double-sided fork, generally comprises a rigid arm, also called a steering arm, on which a swing arm is articulated which ends on the pin of the front wheel. A single-sided swing arm suspension is described for example in European Patent EP2996929B1 .

[ 0003 ] In motorcycle swing arm suspensions of the prior art, the steering arm is mechanically connected to the steering handlebar of the motorcycle. Moreover, the shock absorber group, typically comprising a spring and a damper, is attached to the swing arm.

[ 0004 ] The motorcycle front swing arm suspensions of the prior art described above have several drawbacks.

[ 0005 ] A first drawback is a possible excessive sinking during braking. In effect, during braking, as an effect of the load transfer on the front of the vehicle due to deceleration, the shock absorber group tends to compress and therefore to‘sink’ more than would be the case from the static weight of the vehicle with the driver and any other suspended masses (such as the passenger, baggage and the like).

[ 0006 ] The sinking of the forecarriage, possibly linked to reaching the end of stroke in compression, has as a direct result the significant modification of the attitude of the vehicle.

[ 0007 ] In effect, if one thinks, for example, of a two-wheeled motorcycle, however the same phenomenon also applies to different types of vehicles with more wheels, in the compression phase of the shock absorber group the trail of the vehicle is in particular reduced. Modifying the trail changes the sensitivity and responsiveness of the handlebar perceived by the driver. Moreover, following a poorly controlled and/or excessive sinking, an extension of the rear suspension is generally obtained, which is in turn poorly controlled with consequent lightening of the rear axle until reaching at the limit the condition of detachment of the rear wheel from the ground which may cause the loss of control of the trajectory taken by the driver.

[ 0008 ] It should be noted that the change of attitude during the sinking phase does not necessarily have negative effects a priori. In other words, on the one hand, an excessive sinking is certainly negative, since it involves a change in dynamic attitude that may put the vehicle and the driver in crisis; on the other hand, a controlled sinking of the front suspension may even facilitate and improve the drivability and driving feeling. [ 0009 ] In effect, the driver, due also to the extent of the sinking of the front suspension, is able to perceive the dynamic behavior of the vehicle as well as notice, in advance, that the tire’s grip limit has been reached. In addition, a controlled sinking of the front axle allows a better descent into a bend to take a curve both because it facilitates the lowering of the front axle and because reducing the trail increases the responsiveness and therefore the sensitivity of the driver.

[ 0010 ] As one may deduce from the above, the sinking of the front suspension, called‘dive’, determines, depending on its magnitude, a substantial modification of the dynamic attitude of the vehicle. A controlled type of sinking is not only not harmful but improves the drivability and maneuverability of the vehicle. In this regard, it should be noted that in the swing arm front suspension of said prior art it is not easy to have a controlled sinking of the suspension because there is an interference of the braking force on the stiffness of the suspension.

[ 0011 ] A second drawback of the swing arm front suspensions of the prior art is that the arrangement of the parts close to the wheel hub is not very compact. This lack of compactness leads to both lower cooling efficiency of the brake disc and a lack of aesthetic cleanliness.

[ 0012 ] A third drawback of the swing arm front suspensions of the prior art is that they do not provide adequate protection for the suspension, or at least some parts thereof, from dirt.

[ 0013 ] The general object of the present description is to provide a swing arm motorcycle swing arm front suspension that is capable of resolving, in full or in part, the aforesaid drawbacks.

[ 0014 ] This object is achieved by a motorcycle front suspension as generally defined in claim 1 . Preferred and advantageous embodiments of the aforesaid motorcycle suspension are defined in the accompanying dependent claims.

[ 0015 ] The invention will be better understood from the following detailed description of the particular embodiments thereof made by way of example and, therefore, in no way limiting, with reference to the accompanying drawings briefly described in the subsequent paragraph.

BRIEF DESCRIPTION OF THE DRAWINGS

[ 0016 ] Figure 1 shows a side plan view of a motorcycle comprising a first exemplifying and non-limiting embodiment, of a motorcycle swing arm front suspension wherein said suspension is shown with some parts in cross-section.

[ 0017 ] Figure 2 shows a side view of the motorcycle front suspension of Figure 1 .

[ 0018 ] Figure 3 shows a partial and enlarged side view and with some parts of the suspension of Figure 1 in cross-section.

[ 0019 ] Figure 4 shows a view in cross-section of the suspension of Figure 1 .

[ 0020 ] Figure 5 shows a perspective view of the front suspension of Figure 1 .

[ 0021 ] Figure 6 shows a side view of a second exemplifying and non-limiting embodiment of a motorcycle front swing arm suspension. [ 0022 ] Figure 7 shows a top view of the motorcycle front suspension of Figure 6.

[ 0023 ] Figure 8 shows a view in cross-section of the motorcycle front suspension of Figure 6.

[ 0024 ] Figure 9 shows a partial and enlarged side view and with some parts of the suspension of Figure 6 in cross-section.

[ 0025 ] Figure 10 shows a schematic side view of a third exemplifying and non-limiting embodiment of a motorcycle swing arm front suspension.

[ 0026 ] Figure 1 1 shows a side schematic view of a fourth exemplifying and non-limiting embodiment of a motorcycle swing arm front suspension.

[ 0027 ] Figures 12A and 12B show a schematic view of two respective operating conditions of the motorcycle front suspension according to the present invention.

DETAILED DESCRIPTION

[ 0028 ] In the accompanying figures, identical or similar elements have been indicated at the same numerical references.

[ 0029 ] The accompanying figures show an embodiment of a transport vehicle and, in particular, of a motorcycle 1 . In the particular example represented in the figures, the motorcycle 1 is conceived, without thereby introducing any limitation, as a moped, comprising a front wheel 2 and a rear wheel 3, a drive motor 4, a support frame 5, a saddle 6, a steering handlebar 7 rotatably fixed to the support frame 5 so as to be able to rotate about a steering axis Z-Z.

[ 0030 ] For the purposes of the present description, the term‘motorcycle’ is to be considered in the broad sense, comprising any motorcycle having at least two wheels, i.e., a front wheel 2 and a rear wheel 3. Such definition includes, therefore, also motorcycles having three wheels, including for example two paired steering wheels on the front axle and one drive wheel on the rear axle, but also motorcycles comprising a single steering wheel on the front axle and two drive wheels on the rear axle. Finally, also included in the definition of a motorcycle are so- called quadricycles, which have two wheels on the front axle and two wheels on the rear axle.

[ 0031 ] As is well known, the motorcycle 1 further comprises a head tube 8 fixed to the steering handlebars 7 so as to rotate integrally with the latter about a steering axis Z-Z.

[ 0032 ] The motorcycle 1 further comprises a motorcycle front suspension 10 adapted and configured to secure the front wheel 2 to the steering tube 8, so that this front suspension 10 is operatively interposed between the steering tube 8 and the front wheel 2.

[ 0033 ] The drive motor 4 is directly or indirectly operatively connected to a drive wheel of the motorcycle 1 , in the example, to the rear wheel 3. According to a possible embodiment, the drive motor 4 is an internal combustion engine. According to an alternative embodiment, the drive motor 4 is an electric or hybrid motor. [ 0034 ] Although in the particular examples represented and described the motorcycle front suspension 10 is a single-arm front suspension, cantilevered on one side of the front wheel 2, it should be noted that the teachings of the present patent application are also applicable to double-arm suspensions, i.e. fork suspensions.

[ 0035 ] The motorcycle front suspension 10 comprises a steering arm 1 1 , mechanically connected or suitable to be mechanically connected to the steering handlebar 7 of the motorcycle 1 . In the particular non-limiting example shown in the figures, the steering arm 1 1 has a portion of the upper end connected to the steering tube 8, so that it may rotate in an integral manner with the latter about the steering axis Z-Z. It should be noted that the steering arm 1 1 and the steering tube 8 may be two separate, mechanically coupled pieces but may also form one piece.

[ 0036 ] The motorcycle front suspension 10 further comprises a swing arm 12 having a first connection portion 13 which rotatably connects the swing arm 12 to the steering arm 1 1 and a second connection portion 14 adapted to connect the swing arm 12 to the associable front wheel 2.

[ 0037 ] The motorcycle front suspension 1 further comprises a shock absorber group 20 having an attachment foot 22, rotatably joined to the oscillating arm 12. The first connection portion 13 of the swing arm 12 rotatably connects the swing arm 12 to the steering arm 1 1 so that the swing arm 12 rotates with respect to the steering arm 1 1 about a fulcrum 15 which is movable with respect to the steering arm 1 1 . Preferably, the first connection portion 13 is a first end portion of the swing arm 12 rotatably joined to the steering arm 1 1 to rotate about the movable fulcrum 15, and the second connection portion 14 carries a rotation pin 16 of said associable front wheel 2.

[ 0038 ] In accordance with a particularly advantageous embodiment, the motorcycle front suspension 10 comprises a disc brake caliper 28 fixed to the swing arm 12. For example, the disc brake caliper 28 is part of a braking device 28,29 of the motorcycle 1 comprising, in addition to the caliper 28, a disc 29 for a disc brake fixed to the front wheel 2 so that it may rotate together with the latter. The attachment of the caliper 28 to the swing arm 12 advantageously makes it possible to reduce the sinking of the motorcycle front suspension 10 during braking and to make the suspension 10 particularly tidy and compact in the vicinity of the hub of the front wheel 2. For example, the caliper is fixed to the swing arm 12 by means of a support bracket 125. Preferably, the second connection portion 14 of the swing arm 12 is arranged between the first connection portion 13 and the support bracket 125 of the caliper 28. For example, the support bracket 125 is a plate-shaped bracket.

[ 0039 ] Preferably, the second connection portion 14 carries a rotation pin 16 of the associable front wheel 2. This rotation pin 16 defines an axis of rotation X-X for the front wheel 2. Preferably, the rotation pin 16 of the front wheel 2 has an end portion engaged and tightened by interference in a locking seat defined inside the swing arm 12 and has a further portion that protrudes outside of said locking seat so that it may rotatably support the front wheel 2. More preferably, the aforesaid end portion of the rotation pin 16 is tightened within the aforesaid locking seat so as to prevent a relative rotation between the rotation pin 16 and the swing arm 12,32.

[ 0040 ] In accordance with an advantageous embodiment, the swing arm 12 comprises a third connection portion interposed between the first connection portion 13 and the second connection portion 14. Due to the third connection portion, the swing arm 12 is rotatably connected to the attachment foot 22 of the shock absorber group 20. For example, the motorcycle front suspension 10 comprises a hinge pin 18 that penetrates or is engaged in the third connection portion of the swing arm 12 to join rotatably the attachment foot 22 of the shock absorber group 20 to the swing arm 12.

[ 00 1 ] In accordance with a particularly advantageous embodiment, the attachment foot 22 is rotatably joined to the swing arm 12 so that the swing arm 12 may rotate with respect to the attachment foot 22 about an axis of rotation that may only move along an axis of travel in relation to the steering arm 1 1 . This is made possible by the fact that the fulcrum 16 is movable with respect to the steering arm 1 1 .

[ 0042 ] In accordance with an advantageous embodiment, the steering arm 1 1 is internally hollow, e.g. tubular, and houses at least part of the shock absorber assembly 20 therein. This expedient has the advantage of reducing the exposure of the shock absorber group 20 to dirt and weather.

[ 0043 ] Preferably, the shock absorber group 20 comprises an attachment head 21 fixed to the steering arm 1 1 , for example also arranged inside the steering arm 1 1 . Said attachment head 21 may preferably be hinged by means of the hinge 34 to the steering arm 1 1 .

[ 0044 ] According to a preferred embodiment, in the motorcycle front suspension 10, the shock absorber group 20 comprises a spring 23 and a damper 24,25, and the spring 23 is entirely housed in the steering arm 1 1 . The spring 23 is, for example, a helical spring interposed between the attachment head 21 and the attachment foot 22 of the shock absorber group 20 in order to exert an elastic thrust force that tends to move the attachment head 21 and the attachment foot 22 apart. The spring 23 preferably surrounds the damper 24.

[ 0045 ] Preferably the damper comprises a stem 24 and a sheath 25, and the stem 24 is adapted and configured to slide inside the sheath 25 and is housed in the steering arm 1 1 . Also, this expedient has the advantage of reducing the exposure of the shock absorber group 20, and in particular the stem 24, to dirt and weather. Preferably the attachment foot 22 of the shock absorber group 20 is arranged at the base of the sheath 25.

[ 0046 ] Figures 1 to 5 describe a first embodiment of a motorcycle front suspension 10 in accordance with the present invention. [ 0047 ] Apart from the general characteristics described, in the first embodiment the movable fulcrum 15 is a yielding fulcrum. For example, the first connection portion 13 of the swing arm 12 is rotatably hinged to the swing arm 12 by means of a cylindrical hinge which is elastically fixed between the steering arm 1 1 and the first connection portion 13. As may be seen in Figures 3 and 4, the rotation fulcrum 15 has a hinge pin which penetrates a hole defined in the first connection portion 13 and which is fixed to the support arm 1 1 by elastic support means 19. These elastic support means comprise at least one silent block 19, in the example a pair of silent blocks 19 arranged on opposite sides to the swing arm 12 and arranged in two respective housings defined in the steering arm 1 1 . The general principle of the embodiment of the suspension 10 shown in figures 1 to 5 is thus to ensure the mobility of the fulcrum 15 by elastic support means 19 of the fulcrum 15 operatively interposed between the first connection portion 13 of the swing arm 12 and the steering arm 1 1 , which is why the fulcrum 15 may be defined as a yielding fulcrum. In accordance with a particularly advantageous embodiment, the aforesaid elastic support means have a directionally selective elasticity, i.e. the elastic deformation is greater along a defined direction (e.g. a radial direction with respect to the rotation pin 16) with respect to at least one different direction (e.g. a direction parallel to the steering axis).

[ 0048 ] In an alternative solution, the fulcrum 15 could be a slidable fulcrum and this characteristic could be obtained by providing, for example, for the first connection portion 13 of the swing arm 12, for having a slotted hole, i.e. extended along a direction of extension, inside of which the hinge pin that defines the rotation fulcrum is engaged. In this way, it would be possible to provide for the aforesaid hinge pin to be fixed to the steering arm 1 1 in such a way as to be fixed. The slotted hole may be through or blind. The aforesaid direction of extension is preferably parallel to the ground. The general principle of this alternative embodiment is to provide a linear guide that allows a translation of the fulcrum 15. It is clearly possible to provide for a combined solution that provides for both the elastic support means 19 of the fulcrum 15 and for the possibility of the fulcrum 15 to slide along a linear guide.

[ 0049 ] In accordance with an advantageous embodiment, consistent with the example of Figures 1 -5, the steering arm 1 1 comprises a housing 30 having a chamber 31 within which the first connection portion 13 is arranged. The housing 30 has a through opening 32 penetrated by the swing arm 12 so that the second connection portion 14 is arranged outside of the housing 30. Advantageously, the motorcycle front suspension further comprises an elastically deformable cap 33 fixed to said housing 30 to close the through opening 32. This significantly reduces the exposure of the shock absorber group 20 and a portion of the swing arm 12 to dirt. In accordance with a particularly advantageous embodiment, the elastically deformable cap 33 has a through-hole penetrated by the swing arm 12. In the particular example shown in Figures 1 -5, there are two elastic supports for the movable fulcrum 15, in particular two silent blocks, housed in two seats defined in two opposing walls of the housing chamber 30.

[ 0050 ] Figures 6 to 9 show an alternative embodiment very similar to the one described above and which differs from the latter in that the swing arm 12 comprises a first branch 121 and a second branch 122 arranged parallel to each other, and a bridge portion 123 that connects said branches 121 ,122. The two branches 121 , 122 are configured and arranged in such a way that the attachment foot 22 of the shock absorber group 20 is placed between them. In other words, in this alternative embodiment, the swing arm 12 is a fork arm. In contrast to the embodiment of Figures 1 to 5, no housing chamber 30 is provided.

[ 0051 ] In the embodiment of the Figures 6-9 the fulcrum 15 is movable because, similarly to that which has already been described in the embodiment of the Figures 1 -5, the motorcycle front suspension 10 comprises elastic support means 19 of the fulcrum 15. In the example the aforementioned means comprise two silent blocks 19, each of which is fixed to a respective branch 121 , 122 of the swing arm 12, in particular inserted in a respective housing seat.

[ 0052 ] The motorcycle front suspension 10 preferably comprises a rotatable coupling block 124, which rotates about the fulcrum 15 and is operatively interposed between the branches 121 ,122 and the steering arm 1 1 . This rotatable coupling block 124 is preferably T-shaped.

[ 0053 ] In accordance with an advantageous embodiment, the motorcycle front suspension of Figures 6-9 comprises a bellows cap 133, preferably elastic, fixed to a portion of the lower end of the steering arm 1 1 .

[ 0054 ] Also, in this embodiment, the attachment foot 22 of the shock absorber group 20 is rotatably hinged to the third connection portion of the swing arm 12, in the example by means of a hinge pin 18. Preferably, this hinge pin 18 penetrates two slotted holes 128 defined in the steering arm 1 1 so that the hinge pin 18 and thus the attachment foot may travel along a sliding axis with respect to the steering arm 1 1 .

[ 0055 ] Figure 10 shows schematically a further embodiment wherein the movable fulcrum 15 is slidable with respect to the steering arm 1 1 . In particular, the suspension 10 comprises a slider 1 15 rotatably hinged on the fulcrum 15 to the first connection portion 13 of the swing arm 12. The steering arm 1 1 comprises a linear guide that slidably supports the slider 1 15 so that it may move along a guide axis. Preferably, also in this embodiment the second connection portion 14 of the swing arm 12 carries the rotation pin 18 of the front wheel 2, and the attachment foot 22 of the shock absorber group 1 1 is rotatably hinged to a third connection portion of the swing arm 12 interposed between the first connection portion 13 and the second connection portion 14.

[ 0056 ] Figure 1 1 shows schematically a further embodiment wherein the movable fulcrum 15 is rotatable with respect to the steering arm 1 1 . In particular, the front suspension 1 1 comprises an additional rotatable arm 1 13, which is rotatably hinged to the swing arm 12 so that the swing arm 12 may rotate with respect to the additional rotatable arm 1 13 and about the movable fulcrum 15 and which is rotatably hinged to the steering arm 1 1 so that the additional rotatable arm 1 13 may rotate with respect to the steering arm 1 1 with respect to an additional, preferably fixed, fulcrum 1 15. Preferably, also in this embodiment the second connection portion 14 of the swing arm 12 carries the rotation pin 16 of the front wheel 2, and the attachment foot 22 of the shock absorber group 1 1 is rotatably hinged to a third connection portion of the swing arm 12 interposed between the first connection portion 13 and the second connection portion 14.

[ 0057 ] To clarify the movement of the movable fulcrum 15, Figures 12A and 12B illustrate two operating conditions of the suspension of the present invention. In Figure 12B, the wheel 2 (shown with reduced dimensions) moves upwards, e.g. due to a bump in the road surface, and with it the rotation pin 16 also moves upwards. This movement causes the swing arm 12 to rotate and consequently the shock absorber 20 to be compressed. Since the shock absorber group 20 is configured to slide axially in the hollow portion of the steering arm 1 1 and not to rotate about its hinge point 34, a rotation of the swing arm 12 about the hinge pin 18 of the attachment foot 22 of the shock absorber group 20 is configured. Said hinge pin 18 slides up and down along the longitudinal axis of the shock absorber group 20 according to the movement of the front wheel 2. Consequently, as shown in Figures 12A and 12B, the fulcrum 15 moves forward and backward, for example inside the slotted hole forming part of the first connection portion 13. If the fulcrum 15 were not movable or yielding, the suspension 20 would get stuck and its operation would be incomplete or inefficient. Still with reference to Figures 12A and 12B, it should be noted that the fulcrum 15 defines a respective axis 15 '. With the sinking of the suspension, the axis 15' is movable with respect to the steering arm 1 1 . In other words, the axis 15' changes its relative distance with respect to the steering arm 1 1 . Still in other words, taking as reference the rectilinear axis Z-Z, i.e. the steering axis, with the sinking of the suspension the distance d, defined by the perpendicular that passes through the axis 15’ of the fulcrum and intercepts the axis Z- Z, changes. For example, the axis 15’ of the fulcrum 15 goes backward going to increase the relative distance d’.

[ 0058 ] On the basis of what has been explained above, it is thus possible to understand how a motorcycle swing arm front suspension of the type described above may achieve the objects mentioned above with reference to the prior art.

[ 0059 ] In effect, the aforesaid swing arm motorcycle front suspension has an improved ability to react optimally to loads, allowing the pro-dive or anti-dive effect of the front swing arm suspensions of the prior art to be reduced or eliminated.

[ 0060 ] Without altering the principle of the invention, the embodiments and the details of implementation may vary widely with respect to those described and illustrated purely by way of non-limiting example, without thereby departing from the scope of the invention as defined in the accompanying claims.