EP4638992A1

EP4638992A1 - Sequential gearbox

Info

Publication number: EP4638992A1
Application number: EP23838220.4A
Authority: EP
Inventors: Paolo TIRADRITTI
Original assignee: Piaggio and C SpA
Current assignee: Piaggio and C SpA
Priority date: 2022-12-22
Filing date: 2023-12-19
Publication date: 2025-10-29
Also published as: WO2024134490A1; CN120604059A; JP2026501939A

Abstract

Sequential gearbox, comprising at least two rotating shafts on which gearwheels are mounted and at least one gearwheel selection device to allow selective meshing of gearwheels of said two shafts, said selection device comprising at least one engaging sleeve sliding on one said rotating shaft and at least one shift fork for said sleeve provided with an interaction portion with said sleeve and with a portion slidingly coupled to at least one movement rod of the fork so that a sliding of said fork along said movement rod causes a movement of the sleeve, wherein said at least one movement rod is provided internally, for at least part of its extension, with a duct operatively connected with a lubrication oil distribution system, and wherein along said movement rod there is at least one passage toward the surface of the first rod adapted to allow the outflow of the oil from said duct, and wherein when said gearbox is installed, said passage is orientated downward, so that the lubrication oil flows out from the passage, detaching from said movement rod and falling downward.

Description

SEQUENTIAL GEARBOX

Description

Technical field

[0001] The present invention relates to the field of mechanical transmission systems for vehicles, and more particularly its object is a gearbox of the sequential type. The object of the invention is also a saddle-ride vehicle using said sequential gearbox.

Prior art

[0002] As is known, modern motorcycles are equipped with sequential gearboxes with multi-speed front engagement.

[0003] In the gearbox there are two or more shafts that carry the gearwheels (the gears). In practice there is a power input axis coming from the engine, and an output axis that brings power, by means of a transmission, to one or more wheels of the vehicle. Obviously the input and output rotation speeds are different depending on the transmission ratio set.

[0004] To change the gear ratio, the gearbox is provided with engaging forks, provided with guide pins, which interact with the gearwheels of the gearbox by means of sleeves sliding on the rotating shafts on which the gearwheels are mounted. The forks are installed on a rotating rod, or drum, provided with grooves on which the fork guide pins slide. By rotating the rod, for example by means of a ratchet connected to the gear lever available to the pilot, a fork moves along the rod according to the shape of the grooves (it is in practice a guided coupling), thus moving the sleeve on the shaft. The sleeve may slide axially on the shaft and is however constrained to rotate integrally with it. A gearwheel (or two gearwheels) may be provided on a sleeve, which may therefore translate with the sleeve on the respective shaft and rotate integrally with it. Other gearwheels of the transmission are fixed to the respective shaft on which they are mounted (generally the gearbox input or output one), while others are free to rotate about the shaft without being able to translate on it. Each sleeve is provided with an engaging system in the axial direction with the wheels free to rotate on the shafts, so when the sleeve is engaged on a free wheel, this is prevented from rotating freely and is forced to rotate integrally with the shaft. Depending on the various engagement combinations, the various transmission ratios are thus created.

[0005] The lubrication of the gearbox gears generally occurs by introducing lubricating oil into the gearbox from a distribution system, which is provided with a distribution pump. The oil is introduced into the gearbox through a small straight tube, parallel to the axes of the gearbox shafts, provided with oil drain holes along its extension.

[0006] However, such tube may be subject to breakage, with the consequent risk of it coming loose or bending and interfering with the gearbox gears.

[0007] Furthermore, its position is limited by the little free space inside the gearbox and therefore the effectiveness of oil distribution may not be optimal.

Summary

[0008] The object of the present invention is to solve the drawbacks associated with the lubrication of a sequential gearbox.

[0009] In relation to such object, another important object of the present invention is to create a sequential gearbox which allows the gearbox components to be reduced.

[0010] Another important object of the present invention is to create a sequential gearbox which is reliable in operation.

[0011] Another important object of the present invention is to create a sequential gearbox which has improved lubrication.

[0012] These and other objects that will become apparent hereinafter are achieved with a front engagement gearbox, comprising at least two rotating shafts on which gearwheels are mounted and at least one gearwheel selection device to allow selective meshing of gearwheels of said two shafts, said selection device comprising at least one engaging sleeve sliding on one said rotating shaft and at least one shift fork for said sleeve provided with an interaction portion with said sleeve and with a portion slidingly coupled to at least one movement rod of the fork so that a sliding of said fork along said movement rod causes a movement of the sleeve, characterised in that said at least one movement rod is provided internally, for at least part of its extension, with a duct operatively connected with a lubrication oil distribution system, and wherein along said movement rod there is at least one passage toward the surface of the first rod adapted to allow the outflow of the oil from said duct.

[0013] Such configuration allows lubrication oil to be brought into the gearbox, and to optimize lubrication, reducing the number of components inside the box (the traditional lubrication tube is eliminated, as this is actually integrated into the movement rod of the fork that moves the engaging sleeves).

[0014] Preferably, when the gearbox is installed, the passage is oriented downwards, so that the lubricating oil outflows from the passage, detaching itself from the movement rod and falling downwards.

[0015] The gearbox is intended to be implemented for example when the vehicle V on which the gearbox is mounted is in driving configuration, for example when the rotation axes of the vehicle wheels are approximately horizontal.

[0016] Preferably, when the gearbox is installed, the movement rod of the fork is arranged at a higher height than a rotating shaft carrying gearwheels of the gearbox, in such a way that the movement rod is at least partly superimposed on gearwheels mounted on said shaft and the lubrication oil outflowing from said at least one passage is adapted to fall at least in part on at least one gearwheel mounted on said shaft and/or on said at least one sleeve and/or on the shaft itself. Preferably the shaft is a different shaft than the one on which the at least one sleeve moved by the at least one fork coupled with the movement rod provided with at least one passage from which the lubrication oil outflows is mounted.

[0017] Such configuration allows the arrival of the oil in the most appropriate positions to be optimised.

[0018] According to preferred embodiments, the at least one passage for outflow of the lubrication oil from the duct inside the movement rod is positioned over a said sleeve, so that the oil falling from the movement rod lubricates at least said sleeve and preferably at least the area of said sleeve that interacts with the interaction portion with a respective fork.

[0019] According to preferred embodiments, the at least one passage is provided in proximity to the sliding portion of a fork on the movement rod, so that the passage facilitates lubrication of the surface of the movement rod on which the fork slides.

[0020] According to preferred embodiments, the axis of the at least one movement rod provided with at least one passage for the oil and the axis of one said rotating shaft lie on a same plane that is more or less vertical when the gearbox is arranged installed; preferably, the axis of said at least one passage extends on such plane, so that the passage is arranged more or less vertically; preferably, on said movement rod provided with at least one passage for the oil there is slidingly one said fork adapted to move a sleeve arranged on a different rotating shaft to the one placed on said more or less vertical plane.

[0021] According to preferred embodiments, the gearbox comprises an actuation shaft adapted to interact with said at least one sleeve movement fork in such a way that a rotation of said actuation shaft causes a movement of said at least one fork along said movement rod; preferably, between said at least one fork and said actuation shaft there being a coupling, more preferably said actuation shaft comprising a cam-shaped portion and said at least one fork comprising a pawl adapted to slide relatively in said cam-shaped portion.

[0022] According to preferred embodiments, at least one gearwheel is integrated on said at least one sleeve.

[0023] More in detail, the invention may relate to a sequential gearbox comprising:

- a power input axis and a power output axis,

- at least two rotating shafts, respectively a first rotating shaft and a second rotating shaft, parallel to each other,

- a first assembly of first gearwheels mounted on said first rotating shaft, at least one first first gearwheel and one second first gearwheel of said first assembly being free to rotate about the axis of said first shaft independently from the rotation of said first shaft itself,

- a second assembly of second gearwheels mounted on said second shaft, two second wheels of which being meshed to said first first gearwheel and second first gearwheel, respectively,

- at least a first selection device for said at least one first first gearwheel and at least one second first gearwheel of the first assembly of first wheels, comprising

- at least one first engaging sleeve axially sliding on said first rotating shaft and forced to rotate integrally with said first shaft, said at least one first sleeve being allowed to couple with/decouple from at least said first first gearwheel or with or from at least said second first gearwheel, so that when said first first gearwheel or second first gearwheel is coupled with said first sleeve, said first first gearwheel or said second first wheel is adapted to rotate integrally with said first shaft,

- a first shift fork for said first sleeve, provided with an interaction portion with said first sleeve to be able to move it along said first shaft,

- a first movement rod of said first fork, parallel to said first and second rotating shaft, to which said first fork is slidingly coupled in such a manner that a movement of the fork along said first rod causes a movement of the sleeve coupled thereto on the first shaft, wherein the first movement rod is provided internally, for at least part of its extension, a duct operatively connected with a lubrication oil distribution system, and wherein at least one passage towards the surface of the first rod, adapted to allow the outflow of the oil from said duct, is present along the first rod; preferably said gearbox comprising an actuation shaft adapted to interact with said first fork in such a way that a rotation of said actuation shaft causes the movement of said first fork along the movement rod.

[0024] Preferably, when said gearbox is installed, said first movement rod of the first fork is arranged at a greater height relative to said second shaft in such a manner that said first rod is at least partly positioned over second gearwheels mounted on said second shaft and said lubrication oil outflowing from said at least one passage is adapted to fall at least partly onto at least one second wheel mounted on said second shaft and/or onto said second shaft.

[0025] According to preferred embodiments, the gearbox comprises at least one second selection device for at least two gearwheels of said second assembly of second gearwheels mounted on said second shaft, comprising: at least one second engaging sleeve axially sliding on said second rotating shaft and forced to rotate integrally with said second shaft, said at least one second sleeve being allowed to couple with/decouple from a second gearwheel mounted, with freedom to rotate axially, on said second shaft, so that when said second gearwheel is coupled with said second sleeve, said second wheel is adapted to rotate integrally with said second shaft, a second shift fork for said second sleeve, provided with an interaction portion with said second sleeve to be able to move it along said second shaft, a second movement rod for said second fork, parallel to said first and second rotating shaft, to which said second fork is slidingly coupled in such a manner that a movement of the second fork along said second rod causes the movement of the second sleeve coupled thereto on the second shaft; preferably said gearbox comprising an actuation shaft common to both said first and second selection devices adapted to interact with said first and second forks in such a way that a rotation of said actuation shaft causes movements of said first and second forks along the respective movement rods; preferably at least one second gearwheel, preferably two second gearwheels, being integrated on said at least one second sleeve.

[0026] Preferably, said at least one passage for outflow of the lubrication oil from the duct inside said first rod is positioned over said at least one second sleeve, so that the oil falling from said first rod lubricates at least said second sleeve and preferably at least the area of said second sleeve that interacts with the interaction portion with said second sleeve/second fork. [0027] Preferably, the at least one said passage is provided in proximity to the sliding portion of said first fork on said first rod, so that said passage facilitates lubrication of the surface of said first rod on which the first fork slides.

[0028] Preferably, the axis of said first movement rod and the axis of said second rotating shaft lie on the same plane which is approximately vertical when the gearbox is installed; preferably the axis of said at least one passage extends on said plane, so that the passage is arranged approximately vertically.

[0029] Preferably, at least one first gearwheel, preferably two first gearwheels, are integrated on said at least one first sleeve.

[0030] Preferably, the gearbox comprises a single said first rotating shaft whose axis coincides with said power input axis and a single said second rotating shaft, whose axis coincides with said power output axis; preferably, said first selection device for said first rotating shaft comprises a single first sleeve with two first gearwheels integrated and said second selection device for the second transmission shaft comprises two second sleeves each with a single second gearwheel integrated; preferably, said gearbox being a six-speed gearbox, more preferably on said first shaft there being present, in succession,

- a first wheel fixed on the first shaft adapted to always rotate integrally with said first shaft,

- said first first wheel, free to rotate about the axis of said first shaft independently from the rotation of the first shaft itself,

- said first sleeve on which two third first wheels are integrated, adapted to rotate integrally with said first sleeve,

- said second first wheel, free to rotate about the axis of said first shaft independently from the rotation of the first shaft itself,

- a further first wheel fixed on the first shaft adapted to always rotate integrally with said first shaft; and wherein said two third first wheels on the first sleeve being adapted to be en- gaged/disengaged laterally (i.e. axially) to/from said first first wheel or to said second first wheel by the movement of said first sleeve moved by said first fork; preferably on said second shaft there being present, in succession,

- a first second gearwheel, free, i.e. mounted on the second shaft so as to be able to rotate on it independently of the rotation of the same second shaft, and also unable to move axially along the shaft; preferably such first second free gearwheel is engaged with the first fixed wheel mounted on the first shaft;

- a first second sleeve on which a fifth second gearwheel is integrated, so as to rotate and translate integrally with it; preferably, said fifth second wheel is engaged with the first free wheel mounted on the first shaft;

- a second second gearwheel, free, i.e. also mounted on the second shaft so as to be able to rotate on it independently of the rotation of the same second shaft, and also unable to move axially along the shaft; preferably, such second second gearwheel is engaged with the third first wheel 1 integrated on the first sleeve provided on the first shaft;

- a third second gearwheel, free, i.e. mounted on the second shaft as well so as to be able to rotate on it independently of the rotation of the same second shaft, and also unable to move axially along the shaft; preferably such third second gearwheel is engaged with the further third first wheel integrated on the first sleeve provided on the first shaft;

- a second second sleeve on which a sixth second gearwheel is integrated, so as to rotate and translate integrally with it;

- a fourth second gearwheel, free, i.e. mounted on the second shaft as well so as to be able to rotate on it independently of the rotation of the same second shaft, and also unable to move axially along the shaft; preferably said fourth second gearwheel is engaged with the further first fixed wheel mounted on the first shaft.

[0031] According to preferred embodiments, on the sleeve portion of the at least one fork sliding on said at least one movement rod there may be at least one second- ary through hole which allows the oil present between said at least one movement rod and said sleeve portion of said at least one fork sliding on the movement rod to be able to fall downwards, so as to further lubricate the components located below; preferably, said at least one secondary through hole is inclined with respect to the axis of said at least one movement rod.

[0032] According to preferred embodiments, on said at least one movement rod, in a position preferably included in the stroke space of the sleeve portion of the fork, on said at least one movement rod, there may be a further passage which connects the inside of said duct operatively connected with a lubrication oil distribution system, with the surface of said at least one movement rod; preferably on the internal surface of the sliding tube portion of said at least one fork, on said at least one rod there may be a recess to allow the presence of oil, onto which said further passage faces.

[0033] According to preferred embodiments, the gearbox, under the gearwheels mounted on the lowest rotation shaft in the box itself, has a bottom portion at least partially counter-shaped to said wheels of the lowest shaft, so to form depressions underneath these which are at a distance from the periphery of the respective facing wheels of between 2 and 8 mm, and more preferably between 3 and 7 mm.

[0034] Preferably, between two consecutive depressions, there are projections, which are at a distance from the periphery of the respective facing wheels of between 2 and 8 mm, and more preferably between 3 and 7 mm.

[0035] According to another aspect thereof, the invention relates to a saddle-ride vehicle, comprising an engine provided with a power output axis, and a power transmission from the engine to at least one wheel of the vehicle, wherein a sequential gearbox according to one or more of the preferred configurations disclosed above is operatively arranged between said engine output axis and said transmission.

Brief description of the drawings

[0036] The invention will be better understood by following the description and accompanying drawings, which illustrate an exemplary and non-limiting embodiment of the invention. More particularly, in the drawing: Fig. 1 represents a portion of the engine of saddle-ride vehicle partially sectioned along a vertical plane orthogonal to the engine axis, in which the gearbox according to the invention is visible;

Fig. 2 represents a portion of the engine of Figure 1, with the gearbox associated with it, sectioned along a vertical plane passing through the power output axis of the gearbox;

Fig. 3 represents an axonometric view of gearbox components, according to the invention, extracted from the gearbox;

Fig. 4 represents a front axonometric view of components of a gearbox as in the preceding figures;

Fig. 5 represents a saddle-ride vehicle with a gearbox according to the invention.

Detailed description of embodiments

[0037] With reference to the previously cited figures, a saddle-ride vehicle using a gearbox according to the invention is generally indicated with letter V.

[0038] Vehicle V includes an engine M, for example of the combustion type. Figure 1 shows an engine showing a cylinder and a piston, which move a drive shaft operatively connected, via a clutch, to a gearbox 10, contained inside the box S, for example integrated into the engine casing.

[0039] The power output of the engine is associated with one operating end of the clutch, while the opposite operating end of the clutch is associated with a first rotating shaft 12 which defines the axis X of power input to the gearbox 10. On this first rotating shaft 12, also called primary shaft, a first assembly of first gearwheels R1 is provided.

[0040] In this example, the gearbox is of the six-speed type.

[0041] In this example, in the first assembly R1 there are six first gearwheels mounted on the first shaft 12. In particular, there are present, in succession from the clutch away from it, a first fixed wheel 13, adapted to always rotate integrally with the first shaft, and a first first wheel 14, free, i.e. mounted on the first shaft 12 (for example by means of a bearing) so as to be able to rotate on it independently from the rotation of the same first shaft 12, and also unable to move axially along the shaft 12.

[0042] Downstream of such first free wheel 14, there is a second first free wheel 15, i.e. also mounted on the first shaft so as to be able to rotate independently from the rotation of the same first shaft, and also unable to move axially along the shaft.

[0043] Immediately in succession to the second first free wheel 15, there is a further first fixed wheel 16, mounted on the first shaft 12 so as to always rotate integrally with it.

[0044] Between the first first wheel 14 and the second first wheel 15, there is a first engaging sleeve 17 which is mounted on the first shaft 12 in such a way that it may slide axially on the shaft, but is prevented from being able to rotate freely on it, that is, when the first shaft 12 rotates, the first sleeve 17 rotates integrally with it.

[0045] On the first sleeve 17, at opposite axial ends thereof, two third first wheels 18 and 19 are provided. Such third first wheels are integrated on the first sleeve 17 so as to rotate and translate integrally with it.

[0046] The first sleeve 17 is adapted to couple and uncouple, on command, alternatively with the first first gearwheel 14 and with the second first gearwheel 15 by means of a coupling with engagement teeth, for which two series of engagement teeth 18' and 19' provided on the opposite sides of the first sleeve and directed parallel to the axis of the first shaft 12, or upon the movement of the sleeve 17 on it, are adapted to enter into corresponding engaging seats 14', 15' obtained in the first free gearwheel 14 and second free gearwheel 15 respectively, so when the first sleeve 17 is arranged adjacent to the first first wheel 14, the latter is forced to rotate integrally with it, or with the first shaft 12. Similarly, when the first sleeve 17 is adjacent to the second gearwheel 15, the latter is forced to rotate integrally with it, or with the first shaft 12. The first sleeve 17 may also take a third position, i.e. a neutral position with respect to the first first wheel 14 and second first wheel 15, i.e. it is not coupled to any of the two wheels just mentioned. [0047] The first selection sleeve 17 is part of a first selection device 20 for the first first gearwheel 14 and for the second first gearwheel 15 of the first first wheel assembly Rl.

[0048] A first fork 21 for moving the first sleeve 17 along the first shaft 12 also forms part of such first selection device 20. To be able to move such sleeve, the first fork 21 is provided with an interaction portion 22, with a fork shape (i.e. a "C" shape) to be housed in an annular groove 17A of the sleeve 17 itself.

[0049] The first selection device 20 also includes a first movement rod 23 for the first fork 21. This first rod 23 is parallel to the first shaft 12 and a sleeve-shaped sliding portion 24 of the first fork 21 is slidingly coupled onto it. The movement of the sliding sleeve portion 24 of the first fork 21 along the first movement rod 23 is achieved for example by an actuation shaft 25 (visible only in Figures 1 and 4), with a rotation axis parallel to the first movement rod 23, which may be managed by the driver (for example using a gear lever) of the vehicle V or automatically by software integrated into a control unit of the vehicle. In practice, the actuation shaft 25 is, for example, adapted to interact with the first movement fork 21 in such a way that a rotation of the actuation shaft causes a movement of the first fork along the first movement rod 23 (and therefore of the relative sleeve along the respective rotating shaft).

[0050] For example, between the sleeve portion 24 of the first fork 21 and the actuation shaft 25 there is a cam coupling (for example the actuation shaft 25 includes a portion with cam shaping 26 and the first fork 21 comprises, on the outside of the sleeve portion 24, a pawl 27 adapted to slide relatively in said portion with cam shaping 26) which forces the first fork 21 to move parallel to the axis of the first rod 23 while the actuating shaft 25 rotates.

[0051] The axis Y of power output from the gearbox is created, in this example, by a second rotating shaft 30, also called secondary shaft, parallel to the first shaft 12, on which a second assembly R2 of second gearwheels is provided. In this example there are six second gearwheels.

[0052] In particular, on the second shaft 30, starting from the clutch and moving away from it, there is a first second gearwheel 31, free, i.e. mounted on the second shaft 30 so as to be able to rotate on it independently of the rotation of the same second shaft, and also unable to move axially along the shaft; such first second free gearwheel 31 is engaged with the first fixed wheel 13 mounted on the first shaft 12.

[0053] Along the second shaft 30, downstream of the first second free gearwheel 31 there is a second second gearwheel 32, free, i.e. also mounted on the second shaft 30 so as to be able to rotate on it independently of the rotation of the same second shaft 30, and also unable to move axially along the shaft. Such second second gearwheel 32 is engaged with the third first wheel 18 integrated on the first sleeve 17 provided on the first shaft 12.

[0054] Furthermore, along the second shaft 30, immediately downstream of the second second free gearwheel 32 there is a third second free gearwheel 33, i.e. also mounted on the second shaft 30 so as to be able to rotate on it independently of the rotation of the same second shaft 30, and also unable to move axially along the shaft. Such third second gearwheel 33 is engaged with the further third first wheel 19 integrated on the first sleeve 17 provided on the first shaft 12.

[0055] Moreover, along the second shaft 30, downstream of the third second free gearwheel 33 there is a fourth second gearwheel 34, free, i.e. also mounted on the second shaft 30 so as to be able to rotate on it independently of the rotation of the same second shaft, and also unable to move axially along the shaft. Such fourth second gearwheel 34 is engaged with the further first fixed wheel 16 mounted on the first shaft 12.

[0056] Between the first second wheel 31 and the second second free wheel 32, there is a first second engaging sleeve 35 which is mounted on the second shaft 30 in such a way that it may slide axially on the shaft, but is prevented from being able to rotate freely on it, that is, when the second shaft 30 rotates, the first second sleeve 35 rotates integrally with it.

[0057] On such first second sleeve 35, a fifth second wheel 36 is integrated, so as to rotate and translate integrally with it. Such fifth second wheel 36 is engaged with the first free wheel 14 mounted on the first shaft 12. [0058] Similar to the first sleeve 17 described above, the first second sleeve 35 is adapted to couple and decouple, on command, with/from the first second free gearwheel 31 or the second second free gearwheel 32, by means of a clutch tooth coupling, so two series of coupling teeth 36', 36" provided on the opposite sides of the first second sleeve 35 and directed parallel to the axis of the second shaft 30, or to the movement of the sleeve on it, are adapted to enter into corresponding engaging seats 31' and 32' obtained in the first second free wheel 31 and second second free wheel 32 respectively, so that when the first second sleeve 35 is arranged adjacent to the first second wheel 31, the latter is forced to rotate integrally with it, or with the second shaft 30. Similarly, when the first second sleeve 35 is adjacent to the second second gearwheel 32, the latter is forced to rotate integrally with it, or with the second shaft 30. The first second sleeve 35 may also take a third position, i.e. a neutral position with respect to the first second wheel 31 and second second wheel 32, i.e. it is not coupled to any of the two wheels just mentioned.

[0059] Similarly to the first sleeve 17, the first second selection sleeve 35 is part of a second selection device 40 for the first second gearwheel 31 and for the second second gearwheel 32 of the second wheel assembly R2.

[0060] A first second fork 41 for moving the first second sleeve 35 along the second shaft 30 also forms part of such second selection device 40. To be able to move such sleeve, the first second fork 41 is provided with an interaction portion 42, with a fork shape (for example "C" shape) to be housed in an annular groove of the sleeve itself.

[0061] The second selection device 40 also includes a second movement rod 43 for the first second fork 41. Such second rod 43 is parallel to the second shaft 30. The first second fork 41 is arranged to slide on the second rod 43, and in a similar way as provided for the first rod 23. In practice, the first second fork 41 is slidingly coupled to the second rod 43 in such a way that a movement of the first second fork 41 on the second rod 43 causes the consequent concordant movement (i.e. with the same direction of movement of the fork) of the first second sleeve 35 coupled to it on the second shaft 30. [0062] The coupling of the second rod 43 - first second fork 41 is similar to that described for the case of first rod 23 - first fork 21 and will be omitted herein. The sliding sleeve portion of the first second fork 41 on the second rod 43 is numbered 45.

[0063] The movement of the first second fork 41 is similar to the case of the first fork 21. The same actuation shaft 25 is, for example, adapted to also interact with the first second movement fork 41 in such a way that a rotation of the actuation shaft causes a movement of the first second fork 41 along the second movement rod 43 (and therefore of the relative sleeve along the respective rotating shaft).

[0064] For example, between the sleeve portion 45 of the first second fork 41 and the actuation shaft 25 there is a cam coupling (for example the actuation shaft 25 includes a portion with cam shaping 46 and the first second fork 41 comprises, on the outside of the sleeve portion 45, a pawl 47 adapted to slide relatively in said portion with cam shaping 46) which forces the first second fork 41 to move parallel to the axis of the second movement rod 43 while the actuating shaft 25 rotates.

[0065] Similarly, a second second sleeve 50 is disposed between the third second free wheel 33 and the fourth second free wheel 34. Such second second sleeve 50 is similar to the first second sleeve 35. On such second second sleeve 50, a sixth second wheel 37 is integrated, so as to rotate and translate integrally with it. Such fifth sixth second wheel 37 is engaged with the second first free wheel 15 mounted on the first shaft 12.

[0066] The second second sleeve 50 is adapted to couple and uncouple, on command, with/from the third second free gearwheel 33 or with the fourth second free gearwheel 34 by means of a engagement tooth coupling, as for the sleeves described further above, so a detailed description is omitted.

[0067] Similarly to the first second sleeve 35, the second second sleeve 50 is part of the second selection device 40. A second second fork 51 is therefore provided, provided with a sliding portion 52 with a sleeve shape coupled to the second rod 43 and a fork-shaped interaction portion 53 (for example with a "C" shape with a groove present on the same second second sleeve, similarly to the case of the first second sleeve. The operation of the interaction of the second rod 43 with the second second fork 51 and the second second sleeve 50 is analogous to the operation of the first second fork 41 with the first second sleeve 35. For example, between the sleeve portion 52 of the second second fork 51 and the actuation shaft 25 there is a cam coupling (for example the actuation shaft 25 includes a portion with cam shaping 56 and the second second fork 51 comprises, on the outside of the sleeve portion 52, a pawl 57 adapted to slide relatively in said portion with cam shaping 46) which forces the second second fork 51 to move parallel to the axis of the second movement rod 43 while the actuating shaft 25 rotates.

[0068] In practice, in a known way, the operation of the gearbox provides that depending on the angular position around its axis of the actuating shaft 25, the first sleeve 17 of the first selection device 20, and the first second sleeve 35 and the second second sleeve 50 of the second selection device 40 assume predetermined positions. The various combinations of these positions allow obtaining a series of different transmission ratios (each ratio consisting of a "gear") between the power input axis X and the power output axis Y (in this example six combinations, corresponding to six gears).

[0069] To lubricate the gearbox, the supply of lubricating oil is provided by means of a lubricating oil distribution system 60 in the gearbox, a section of which is schematized by a dotted line in Figure 2, which may include a pumping system for the gearbox oil.

[0070] Advantageously, inside the first movement rod 23 there is a duct 60A operationally connected to the oil distribution system 60. In this example, the duct 60A develops in accordance with the axis of the first rod 23, entering from one end of the rod and terminating blindly inside it. Along the extension of the first rod 23 there are a plurality of passages 61, 62, 63 and 64, in practice through holes, which put the inside of the duct 60A in communication with the external surface of the first rod 23 so as to let out the oil from the 60A line and from here be distributed into the gearbox.

[0071] In the preferred examples, such as the one in the description, the passages 61-64 are oriented downwards, so the lubricating oil exits the passage, detaching itself in part from the first movement rod 23 and falling downwards due to gravity (the flow of oil indicated schematically with H). The high-low orientation refers to the gearbox when put into operation, i.e. when the vehicle V on which the gearbox is mounted is in driving configuration, for example when the rotation axes of the vehicle wheels are approximately horizontal.

[0072] Conveniently, in this example, the first rod 23 is arranged at a higher height than at least one shaft, and preferably at a higher height than the second shaft 30, in such a position that this first rod 23 is at least partly overlapped with the second gearwheel assembly R2, so that the oil coming out from the passages 61-64 falls at least in part on at least a second wheel of the assembly R2, or on the sleeve of the assembly R2. Note that, in this example, in practice the oil lubricates a shaft different from that associated with the selection device of which the first rod 23 is part.

[0073] In this example, the axis of the first movement rod 23 and the axis of the second shaft 30 lie on a plane which is vertical or approximately vertical when the gearbox is in operation, as clearly visible in Figure 1 and Figure 4.

[0074] Preferably, the axes of the passages 61-64 extend on such vertical plane and therefore these passages are arranged approximately vertically.

[0075] In practice it is possible to choose, during the design phase, where to release the oil so that it falls into an advantageous position below.

[0076] In particular, a preferred position of at least one passage 61-64 of the duct 60A is for example that of lubricating an area relating to a second sleeve 35, 50. For example a pair of passages 61, 62 is arranged above the first second sleeve 35 so as to lubricate such sleeve, and the second pair of passages 63, 64 are arranged above the second second sleeve 50 to lubricate such sleeve.

[0077] More particularly, for each pair of passages 61, 62 and 63, 64, a passage 61, 64 is superimposed on the respective gearwheel integrated on the respective sleeve 35, 50, while a passage 62, 63 is superimposed on the area of the respective sleeve 35, 50, which interacts with the interaction portion with a respective fork.

[0078] In preferred embodiments, one or more passages 61-64 are provided on the first rod 23 in such a way that they are in proximity to the sliding portion 24 with a sleeve shape 24 of the first fork on the first rod 23, whereby the passage or passages facilitate lubrication of the surface of the rod 23 on which the first fork 21 slides, thus allowing to avoid the introduction of particularly hard material into the holes of the first fork 21 within which the rod 23 slides.

[0079] In this example, the sleeve-shaped sliding portion 24 of the first fork 21 is arranged between the two pairs of passages 61-64, close to them.

[0080] Conveniently, on the sleeve portion 24 of the first fork 21 there may be one or more secondary through holes 24A which allow the oil present between the first rod 23 and the sleeve portion 24 to fall downwards, so as to further lubricate the components located below, such as for example the second second gearwheel 32 and the third second gearwheel 33. Preferably, these secondary through holes 24A, unlike the passages 61-64 which are orthogonal to the axis of the first rod 23, are inclined with respect to such rod, in order to direct the oil into desired positions.

[0081] To facilitate lubrication between the sleeve portion 24 of the first fork 21 and the first rod 23, as well as increase the quantity of oil that may pass through secondary through holes 24 A on the first rod 23, in a position preferably included in the stroke space of the sleeve portion 24 on the same first rod 23, there may be a further passage 65 which connects the inside of the duct 60A with the surface of the first rod 23. Conveniently, on the internal surface of the sleeve portion 24, there may be a recess 24B to allow a slight accumulation of oil.

[0082] It should be noted that an end 23X of the first rod 23, preferably the one opposite the oil inlet into the duct 60A, has a shape coupling with a portion PX inside the gearbox (for example a portion of the preselection plate), such that the angular mounting orientation of the rod 23 around its axis is unique, ensuring that the oil passages 61-64 are correctly oriented downwards. For example, such end 23X has a flattening 23H and correspondingly the portion PX is of a rectilinear shape suitable for coupling with the flattening 23H, so that the rod may be positioned with a single position against the portion PX, without the possibility of rotating.

[0083] Conveniently, the gearbox S, under the lowest gearwheel assembly, or in this example the second gearwheel assembly R2, has a bottom portion at least partially counter-shaped to the second wheels, so as to form underneath these depressions and projections which are at a particularly small distance from the periphery of the wheels. The lubrication oil tends to accumulate in the depressions and the re- duced distance between the bases of the depressions and the periphery of the wheels allows the latter to collect the oil during rotation, thus favouring lubrication and also the distribution of the oil inside the box by means of the tangential splashes caused by the rotary motion of the gearwheels.

[0084] More specifically, on the bottom of the gearbox S there are a plurality of depressions. In this specific example there are three depressions and two projections.

[0085] A first depression SI is obtained at the first second wheel 31, which in this example corresponds to the gearwheel with the largest diameter. For example, the distance between the base, i.e. the bottom, of the first depression SI and the first second gearwheel is between 2 and 5 mm, and more preferably between 3 and 4 mm.

[0086] The bottom of the box S, in the direction from the clutch towards the gearbox exit, rises upwards to define a first projection S2 substantially facing the fifth second gearwheel 36 and whose distance from the latter is between 2 and 5 mm, and more preferably between 3 and 4 mm.

[0087] From the first projection S2, the bottom descends to create a second depression S3, facing the second second gearwheel 32 and the third second gearwheel 33. In this case, the distance between the second depression S3 and the third second wheel 33 (between the two, the larger one) is between 2 and 5 mm, and more preferably between 3 and 4 mm, while the distance between the second depression S3 and the second second gearwheel 32 is between 5 and 8 mm, and more preferably between 6 and 8 mm.

[0088] From the second depression S3, the bottom of the box S rises upwards to define a second projection S4 substantially facing the sixth second gearwheel 37 and whose distance from the latter is between 2 and 5 mm, and more preferably between 3 and 4 mm.

[0089] From the second projection S4, the bottom descends to create a third depression S5, facing the fourth second gearwheel 34, with a distance between them of between 5 and 8 mm, and more preferably between 6 and 8 mm.

[0090] The lubrication system to which the duct 61 is connected may advantageously be pressurized by means of a suitable pump (not shown in the figures). At the inlet of the duct 61 there may be a pressure reducer (not shown in the figures), in order to calibrate the correct pressure of the oil that feeds the duct.

[0091] In this example, only the first rod 23 of the first selection device is provided with the duct 61 with passages for distributing oil into the gearbox. In other embodi- ments, a similar system (conducted with at least one passage, variously oriented, depending on the needs) may be integrated into the second rod of the second selection device.

[0092] Furthermore, the oil distribution system may also be connected with an oil duct made internally to one, or both, of the rotating shafts 12 and 30 on which the gearwheel assemblies R1 and R2 are present, and whose duct is provided with at least one passage through the shaft to let the oil out of the duct and lubricate, for example, the desired surface areas thereof.

[0093] It is understood that what has been illustrated represents only possible nonlimiting embodiments of the invention, which can vary in forms and arrangements without departing from the scope of the concept underlying the invention. The possible presence of reference numbers in the attached claims has the sole purpose of facilitating the reading thereof in the light of the foregoing description and the accompanying drawings and does not in any way limit the scope of protection.

Claims

1. Sequential gearbox, comprising at least two rotating shafts on which gearwheels are mounted and at least one gearwheel selection device to allow selective meshing of gearwheels of said two shafts, said selection device comprising at least one engaging sleeve sliding on one said rotating shaft and at least one shift fork for said sleeve provided with an interaction portion with said sleeve and with a portion slidingly coupled to at least one movement rod of the fork so that a sliding of said fork along said movement rod causes a movement of the sleeve, wherein said at least one movement rod is provided internally, for at least part of its extension, with a duct operatively connected with a lubrication oil distribution system, and wherein along said movement rod there is at least one passage toward the surface of the first rod adapted to allow the outflow of the oil from said duct, and wherein when said gearbox is installed, said passage is orientated downward, so that the lubrication oil flows out from the passage, detaching from said movement rod and falling downward.

2. Gearbox according to claim 1 or 2, wherein when said gearbox is installed, said movement rod of the fork is arranged at a greater height relative to one said shaft so that said movement rod is at least partly positioned over gearwheels mounted on said shaft and said lubrication oil flowing out from said at least one passage is adapted to fall at least partly onto at least one wheel mounted on said shaft and/or onto said sleeve and/or onto said shaft; preferably, said shaft is a different shaft relative to the one on which the at least one sleeve moved by the at least one fork coupled with the movement rod provided with the at least one passage from which the lubrication oil flows out is mounted.

3. Gearbox according to one or more of the preceding claims, wherein said at least one passage for outflow of the lubrication oil from the duct inside said movement rod is positioned over a said sleeve, so that the oil falling from said movement rod lubricates at least said sleeve and preferably at least the area of said sleeve that interacts with the interaction portion with a respective fork.

4. Gearbox according to one or more of the preceding claims, wherein at least one said passage is provided in proximity to the sliding portion of one said fork on said movement rod, so that said passage facilitates lubrication of the surface of said movement rod on which the fork slides.

5. Gearbox according to one or more of the preceding claims, wherein the axis of said at least one movement rod provided with at least one passage for the oil and the axis of one said rotating shaft lie on a same plane that is more or less vertical when the gearbox is arranged installed; preferably, the axis of said at least one passage extends on said plane, so that the passage is arranged more or less vertically; preferably, on said movement rod provided with at least one passage for the oil there is slidingly one said fork adapted to move a sleeve arranged on a different rotating shaft to the one placed on said more or less vertical plane.

6. Gearbox according to one or more of the preceding claims, wherein at least one gearwheel is integrated on said at least one engaging sleeve.

7. Gearbox according to one or more of the preceding claims, comprising an actuation shaft adapted to interact with said at least one sleeve movement fork in such a way that a rotation of said actuation shaft causes a movement of said at least one fork along said movement rod; preferably, between said at least one fork and said actuation shaft there being a coupling, more preferably said actuation shaft comprising a cam-shaped portion and said at least one fork comprising a pawl adapted to slide relatively in said cam-shaped portion.

8. Gearbox according to one or more of the preceding claims, comprising a power input axis and a power output axis, at least two said rotating shafts, respectively a first rotating shaft and a second rotating shaft, parallel to each other, on which said gearwheels are mounted, including a first assembly of first gearwheels mounted on said first rotating shaft, of which at least one first first gearwheel and one second first gearwheel of said first assembly are free to rotate about the axis of said first shaft independently from the rotation of said first shaft itself, a second assembly of second gearwheels mounted on said second shaft, two second wheels of which being meshed to said first first gearwheel and second first gearwheel, respectively, at least one first said selection device for said at least one first first gearwheel and at least one second first gearwheel of the first assembly of first wheels, comprising at least one first engaging sleeve axially sliding on said first rotating shaft and forced to rotate integrally with said first shaft, said at least one first sleeve being allowed to couple with/decouple from at least said first first gearwheel or with or from at least said second first gearwheel, so that when said first first gearwheel or second first gearwheel is coupled with said first sleeve, said first wheel is adapted to rotate integrally with said first shaft, a first shift fork for said first sleeve, provided with an interaction portion with said first sleeve to be able to move it along said first shaft, a first movement rod of said first fork, parallel to said first and second rotating shaft, to which said first fork is slidingly coupled in such a manner that a movement of the fork along said first rod causes a movement of the sleeve coupled thereto on the first shaft, and wherein said first movement rod is provided internally, for at least part of its extension, with a said duct operatively connected with a lubrication oil distribution system, and wherein at least one said passage towards the surface of the first rod, adapted to allow the outflow of the oil from said duct, is present along the first rod; preferably said gearbox comprises at least one second selection device for at least two gearwheels of said second assembly of second gearwheels mounted on said second shaft, comprising at least one second engaging sleeve axially sliding on said second rotating shaft and forced to rotate integrally with said second shaft, said at least one second sleeve being allowed to couple with/decouple from a second gearwheel mounted, with freedom to rotate axially, on said second shaft, so that when said second gearwheel is coupled with said second sleeve, said second wheel is adapted to rotate integrally with said second shaft, a second shift fork for said second sleeve, provided with an interaction portion with said second sleeve to be able to move it along said second shaft, a second movement rod for said second fork, parallel to said first and second rotating shaft, to which said second fork is slidingly coupled in such a manner that a movement of the second fork along said second rod causes the movement of the second sleeve coupled thereto on the second shaft; preferably said gearbox comprising an actuation shaft common to both said first and second selection devices adapted to interact with said first and second forks in such a way that a rotation of said actuation shaft causes movements of said first and second forks along the respective movement rods; preferably at least one second gearwheel, preferably two second gearwheels, being integrated on said at least one second sleeve.

9. Gearbox according to claim 8, wherein when said gearbox is installed, said first movement rod of the first fork is arranged at a greater height relative to said second shaft in such a manner that said first rod is at least partly positioned over second gearwheels mounted on said second shaft and said lubrication oil outflowing from said at least one passage is adapted to fall at least partly onto at least one second wheel mounted on said second shaft and/or onto said second shaft; and/or said at least one passage for outflow of the lubrication oil from the duct inside said first rod is positioned over said at least one second sleeve, so that the oil falling from said first rod lubricates at least said second sleeve and preferably at least the area of said second sleeve that interacts with the interaction portion second sleeve/second fork.

10. A saddle-ride vehicle, comprising an engine provided with a power output axis, and a power transmission from the engine to at least one wheel of the vehicle, wherein a sequential gearbox according to one or more of the preceding claims is operatively arranged between said engine output axis and said transmission.