Patent Description:
Within the field of saddle-ride type vehicles, those provided with a seamless gearbox are known. With respect to a conventional gearbox, in which it is necessary to stop transmission by activating the clutch and interrupting the power supply to the engine to engage the gear, a seamless gearbox does not require any interruption of torque between the engine and the rear wheel of the vehicle. In practice, the seamless gearbox does not disengage a first gear pair to engage the next one, as occurs in a conventional gearbox, but engages the next gear while the one in use is still meshing. In substance, through a known mechanical system, one of the two gears is disengaged as soon as the next gear starts to transmit torque.

It is also known that besides a reduction of the gear change times between one gear and the next, one of the main advantages of the use of a seamless gearbox lies in the more linear delivery of the torque curve generated by the engine and transmitted to the drive wheel. In this regard, in a conventional gearbox, engaging a new gear translates into a force that modifies, through the chain pull, the load on the rear suspension of the vehicle and ultimately the stability of the vehicle. Therefore, in a condition of bending of the vehicle or during a change in direction, the use of a seamless gearbox is particularly advantageous as the chain pull does not vary significantly and therefore the excursion of the suspension is not modified.

However, if on the one hand a seamless gearbox allows gear change without interrupting the transmission (i.e., without operating the clutch), on the other during a gear "upshift" (i.e., from a gear with a lower transmission ratio to a gear with a higher transmission ratio), this aspect leads to an increase (peak) of the torque at the end of the change. In order to prevent breakage of the mechanical components it is thus necessary to limit these torque peaks. Typically, this result is achieved by acting on the control unit of the engine and more precisely by setting it so that the engine is switched off during the change for sufficient time to prevent the torque peak. This control strategy requires perfect synchronization between the gearbox and the switching off and back on of the engine by the control unit.

However, the Applicant has seen that in certain cases the inertia of the drive shaft is so high that it is not affected by any switching off of the engine commanded by the control unit. In other words, the drive shaft continues to rotate at the same speed. Therefore, currently in a condition of inertia of this type, the use of a seamless gearbox does not seem possible in view of the fact that it is not possible to limit, through the action of the control unit, the torque peaks that would occur when the gears are engaged.

Therefore, the Applicant has identified the need to provide a new technical solution that increases the possibilities of use of a seamless gearbox and at the same time allows simplification of the control unit in terms of strategy implemented. For background art, see <CIT>.

The main aim of the present invention is to provide a saddle-ride type vehicle provided with a device for limiting torque peaks during a gear upshift that allows the problems set forth above to be solved. Within this aim, a first object of the present invention is to provide a device that does not require the engine to be switched off and the operation of which is completely independent from the rotation speed of the drive shaft. Another object of the present invention is to provide a device that is reliable and easy to produce at competitive costs.

The Applicant has seen that the aims and the objects indicated above can be reached by causing, at the end of the gear change, a controlled slipping of the clutch (without reaching an opening condition thereof) such as to absorb the torque peak. In particular, the aims and the objects indicated can be achieved by means of a saddle-ride type vehicle comprising an engine, a gearbox and a clutch assembly interposed between the engine and the gearbox, wherein the clutch assembly comprises:.

The vehicle according to the invention comprises a control device of the clutch assembly, wherein this control device comprises an actuation means that, during a gear change performed by means of the gearbox and following a command of a pilot, exerts a predetermined force in contrast to the load of the return means, this predetermined force being less than the force exerted by the return means so as to cause the clutch device to slip without said opening condition being reached.

Again, according to the invention, the operating device of the clutch assembly is of hydraulic type and comprises a primary pump operated by means of a control lever, wherein the primary pump is hydraulically connected, through a primary hydraulic circuit, to a primary piston acting on at least one of the elements in opposition to the return means so as to determine the opening condition. Moreover, the control device comprises a secondary piston connected to the primary piston of the operating device, wherein this actuation means exerts, directly or indirectly, said predetermined force on the secondary piston, wherein said predetermined force is transferred to the primary piston in opposition to the force exerted by the return means.

In accordance with a possible embodiment, the actuation means can be mechanically activated by the pilot when a gear change, preferably a gear upshift, is required. In substance, the actuation means is controlled, directly or indirectly, by the mechanisms on which the pilot acts to command the gear change. In this embodiment, activation of the actuation means does not in fact require any electronic control component.

In accordance with an alternative embodiment, the actuation means can be electronically activated by means of a control unit of the vehicle when this control unit detects a gear change requested by the pilot, for example a gear upshift commanded by the pilot. The intervention of the control unit does not require a particular control strategy, but only the knowledge of the gear engaged or rather of the direction of the gear change (downshift or upshift).

In accordance with a possible embodiment, the secondary piston is activated through a secondary hydraulic circuit that is independent from the primary hydraulic circuit. Preferably, the actuation means is configured so as to generate, when activated, an increase of pressure in the secondary hydraulic circuit.

In a possible embodiment, the actuation means is connected to a control unit of the vehicle that controls activation and deactivation of the actuation means as a function of the gear change commanded by the pilot.

In an alternative embodiment, the actuation means is of hydraulic type and is activated, directly or indirectly, by means of a gear change pedal mechanism on which the pilot acts.

Further features and advantages of the invention will be more apparent from examining the following detailed description of some preferred, but not exclusive, embodiments ot a vehicle illustrated by way of non-limiting example with the aid of the accompanying drawings, wherein:.

The same reference numbers and letters in the figures identify the same elements or components.

With reference to the aforesaid figures, the present invention therefore relates to a saddle-ride type vehicle <NUM> that includes a control device of a clutch assembly of a saddle-ride type vehicle, where said control device allows torque peaks, during a gear change commanded by a pilot, to be limited. Such a device is particularly suitable for a vehicle provided with a seamless gearbox, but could also be applied in a vehicle provided with a gearbox of different type.

For the purposes of the present invention, the expression "saddle-ride type vehicle" is meant generically as any two-wheeled moped or motorcycle provided with a front wheel and with a rear wheel. In the description below, the vehicle <NUM> will also be indicated with the term motor vehicle <NUM> or motorcycle <NUM>. Moreover, for the purposes of the present invention, the expression "gear upshift" is meant as a passage from a lower gear to the next highest gear (e.g., from first gear to second gear or from second gear to third gear). Instead, the expression "gear downshift" or "gear change down" is meant as the passage from a higher gear to the gear immediately below it (e.g., from fourth gear to third gear or from second gear to first gear).

In its general configuration, schematized in <FIG>, a motorcycle <NUM> according to the invention comprises an engine <NUM> and a gearbox <NUM>, preferably, but not exclusively, of seamless type, the operating principle and possible configurations of which are known to those skilled in the art. With reference to the gearbox <NUM>, the gears thereof are engaged by the pilot by means of a mechanism that comprises a pedal lever on which the pilot acts, according to a widely known principle.

Interposed between the engine <NUM> and the gearbox <NUM> is a clutch assembly <NUM> that comprises a clutch device <NUM> and an operating device <NUM> for commanding said clutch device <NUM>. The gearbox <NUM> is provided with an input connected to the clutch device <NUM> and with an output connected, by means of a mechanical transmission <NUM>, to the drive wheel <NUM> of the motor vehicle <NUM>. As a whole, the engine <NUM>, the gearbox <NUM> and the clutch assembly <NUM> form an assembly of components <NUM> supported by the chassis of the motor vehicle <NUM> according to a widely known principle. The clutch device <NUM> comprises at least one drive element 11A (or drive disc 11A) mechanically connected, directly or indirectly, to the shaft of the engine <NUM> and a driven element 11B (or driven disc 11B) integral with the input shaft of the gearbox <NUM>. The clutch device <NUM> further comprises return means <NUM>, in particular of elastic type, for example a spring (of elastic type), configured so as to exert a force such as to keep the two elements 11A, 11B in contact with each other, i.e., in a closure condition of said clutch device <NUM>. In this condition, the motion of the drive element 11A is transferred to the driven element 11B. Possible configurations and construction variants of a clutch device <NUM> having the features described above are widely known to those skilled in the art. In particular, the clutch device <NUM> can be of "multi disc" type, comprising a plurality of drive elements, mechanically connected to the shaft of the engine, and a plurality of driven elements mechanically connected to the input shaft of the gearbox, wherein the return means keep the drive elements in contact with corresponding driven elements.

The operating device <NUM> of the clutch assembly <NUM>, following its activation, causes the mutual detachment of said elements 11A, 11B of the clutch device <NUM>, i.e., disconnects the mechanical transmission between engine <NUM> and gearbox <NUM>. In practice, the operating device <NUM> is configured to switch the condition of the clutch device <NUM> from a closure configuration to an opening configuration.

According to the present invention, the motorcycle <NUM> comprises a control device <NUM> of the clutch assembly <NUM> comprising an actuation means <NUM> that, during gear change (at least upshift), exerts a predetermined force (indicated with S) in opposition to the force (indicated with F) exerted by the return means <NUM> so as to generate a slipping between the elements 11A, 11B without however causing a detachment between said elements. For this purpose, said predetermined force S is therefore less than the force F (hereinafter also indicated with the term "load") exerted by the return means <NUM>, i.e., less than the force that keeps the two elements 11A, 11B of the clutch device <NUM> in contact. Following this condition, as a result of said predetermined force S, during a gear upshift, the transmission of torque between the two elements 11A, 11B is not interrupted, but simply reduced thus absorbing the torque peak that otherwise would be generated as a result of the operating principle of the seamless gearbox.

For the purposes of the present invention, the expression "actuation means" is meant generically as any means formed by one or more elements capable of exerting, when activated, the predetermined force S in the terms indicated above. In particular, the actuation means <NUM> is activated at least during gear upshift and deactivated upon completion of this gear change (i.e., once the higher gear has been engaged). Therefore, activation and deactivation of the actuation means <NUM> depend on the instantaneous configuration of the gearbox <NUM> in reference to which the direction of change (upshift or downshift) is decided and commanded directly by the pilot of the vehicle <NUM>.

Again, according to the invention, the operating device <NUM> of a clutch assembly <NUM> comprises a control device <NUM> according to the invention. This device is of hydraulic type and comprises a primary pump <NUM> operated by means of a control lever <NUM> that can be gripped directly by the pilot (see schematic view in <FIG>). The primary pump <NUM> is hydraulically connected, through a first hydraulic circuit <NUM> to a primary piston <NUM> that acts, directly or indirectly, on one of the two elements 11A,11B of the clutch device <NUM> (not shown in <FIG>). In particular, following operation of the control lever <NUM>, the pressure of the oil in the first hydraulic circuit <NUM>, produced by the primary pump <NUM>, determines a force (indicated with T) that causes a shift of the primary piston <NUM>, in opposition to the load (force indicated with F) of the (elastic) return means <NUM>, and consequently detachment of the two elements 11A, 11B of the clutch device <NUM>.

Always according to the invention, the control device <NUM> comprises a secondary piston <NUM> operatively connected to the primary piston <NUM>, i.e., so that a shift of the secondary piston <NUM> causes a corresponding shift of the primary piston <NUM>. According to this embodiment, the actuation means <NUM> exerts the predetermined force S, indicated above, on said secondary piston <NUM>. This force S is transferred to the primary piston <NUM> in contrast to the load of the return means <NUM> to cause slip of the clutch device <NUM> as indicated above. In any case, the predetermined force S exerted by the secondary piston <NUM> will always be less than the load of the return means <NUM>. Again according to the invention, the control device comprises a secondary hydraulic circuit <NUM> between said actuation means <NUM> and said secondary piston <NUM>. The actuation means <NUM> is configured so as to generate, when activated, an increase of pressure in said secondary hydraulic circuit <NUM>. Such an increase of pressure translates into the predetermined force S on the secondary piston <NUM> and consequently on the primary piston <NUM> for the purposes indicated above.

In a possible embodiment, also schematized in <FIG>, said actuation means <NUM> is connected to a control unit <NUM> that controls its activation and deactivation as a function of the gear engaged by the pilot. Preferably, the control unit <NUM> is the same unit that controls switching on and switching off of the engine <NUM>. The control unit <NUM> of the vehicle <NUM> recognizes the direction of the gear change (upshift or downshift) by means of systems know to those skilled in the art (for example based on the use of a transducer of "quick shifter" type). In a possible embodiment, the control unit <NUM> activates the actuation means <NUM> only when it recognizes a gear upshift, while in the case of a gear downshift, the actuation means <NUM> remains deactivated.

In the case in which the actuation means <NUM> is of hydraulic type, as indicated above, its activation leads to an increase of the pressure of the oil inside the secondary circuit <NUM> which, acting on the secondary piston <NUM>, causes the slipping of the clutch. Upon completion of engagement of the gear, the control unit <NUM> deactivates the actuation means <NUM> thereby returning the clutch device <NUM> to the condition prior to the gear change.

The possibility of the actuation means <NUM> being of electric or electromechanical type and acting directly on the secondary piston <NUM> or alternatively directly on the primary piston <NUM> of the operating device <NUM> also falls within the scope of the present invention.

In accordance with a possible variant of embodiment, schematized in <FIG>, the actuation means <NUM> is of hydraulic type and is directly activated, directly or indirectly, by means of a control lever <NUM> mechanically activated by the pilot when operating the pedal mechanism for engaging the gear. In other words, according to this embodiment, activation of the actuation means <NUM> is performed mechanically and not electronically, i.e., without a direct action of a control unit. In the schematic view of <FIG>, the control lever <NUM> is illustrated as an extension of a gear lever <NUM> of the pedal mechanism connected to the axis <NUM> of the drum of the gearbox <NUM>. Each time that this gear lever is rotated, by means of the intervention of the pilot, in a direction corresponding to a gear upshift, the actuation means <NUM> is activated so as to increase the pressure of the oil in the secondary circuit <NUM> and to cause the slipping of the elements 11A, 11B of the clutch device.

Claim 1:
A saddle-ride type vehicle (<NUM>) comprising an engine (<NUM>), a gearbox (<NUM>) and a clutch assembly (<NUM>) interposed between said engine (<NUM>) and said gearbox (<NUM>), wherein said clutch assembly (<NUM>) comprises:
- a clutch device (<NUM>) comprising at least one drive element (11A) integral with the shaft of said engine (<NUM>), at least one driven element (11B) integral with an input shaft of said gearbox (<NUM>) and return means (<NUM>) that keep said elements (11A, 11B) in contact in a closure condition of said clutch device (<NUM>);
- an operating device (<NUM>) of said clutch device (<NUM>) to cause, in opposition to said return means (<NUM>), a mutual detachment of said elements (11A, 11B) up to an opening condition of said clutch device (<NUM>),
wherein the vehicle (<NUM>) also comprises a control device (<NUM>) of said clutch assembly (<NUM>), wherein said control device (<NUM>) comprises an actuation means (<NUM>) that, during a gear change performed by said gearbox following a pilot command, exerts a predetermined force (S) in contrast to the force (F) exerted by said return means (<NUM>), said predetermined force (S) being less than said force (F) exerted by said return means (<NUM>) so as to cause said clutch device (<NUM>) to slip without said opening condition being reached;
wherein said operating device (<NUM>) is of hydraulic type and comprises a primary pump (<NUM>) operated by means of a control lever (<NUM>), wherein said primary pump (<NUM>) is hydraulically connected, through a primary hydraulic circuit (<NUM>), to a primary piston (<NUM>) acting on at least one of said elements (11A,11B) of said clutch device (<NUM>) in opposition to said return means (<NUM>) so that, as a result of an action on said control lever (<NUM>), said primary piston (<NUM>) exerts an action on said elements (11A,11B) determining said opening condition;
wherein said control device (<NUM>) comprises a secondary piston (<NUM>) connected to said primary piston (<NUM>), wherein said actuation means (<NUM>) exerts, directly or indirectly, said predetermined force (S) on said secondary piston (<NUM>), said predetermined force (S) being transferred to said primary piston (<NUM>) in opposition to said force (F) of said return means (<NUM>).