Patent Description:
This invention relates to a hybrid-drive motorcycle.

As is well known, the need to reduce fuel consumption and emissions has led to the increasing popularity of hybrid traction in the automotive field.

In the motorcycle field, hybrid traction is still not very widespread, and there is a need to optimise the integration between the endothermic engine and the electric machine in order to enable various riding modes with optimal performance and safety conditions.

There is, in addition, a need to minimise the dynamic problems deriving from the mass of the electric machine, and the greater difficulty of placing the electric machine in the reduced space available on a motorcycle.

<CIT> discloses a hybrid-drive motorcycle having the features of the preamble of claim <NUM>.

<CIT> discloses a hybridization kit including an electric motor detachably mountable to the IC engine case of a motorcycle.

The purpose of this invention is to provide a hybrid-drive motorcycle that makes it possible to overcome the above-mentioned drawbacks.

The above-mentioned purpose is achieved with a hybrid-drive motorcycle according to claim <NUM>, comprising a carrier structure, an endothermic engine mounted on or housed in the carrier structure, a front wheel, a rear wheel connected to the carrier structure through a swingarm, a gearbox connected to the endothermic engine through a primary transmission and to the rear wheel through a secondary transmission, a reversible electric machine, an auxiliary transmission connecting a shaft of the electric machine to an input shaft of the secondary transmission, and a support unit secured to the carrier structure and configured to support the electric machine below the swingarm.

The fact that the electric machine is connected to the input shaft of the secondary transmission makes it possible to completely bypass the endothermic engine in purely electric driving mode, switching off the endothermic engine and putting the gearbox in neutral, as well as driving the motorcycle without changing gears.

This arrangement also makes it possible to endow the electric machine with active anti-rearing or anti-spinning control functions by exerting a braking torque and simultaneously recharging the batteries without having to intervene on the power cut of the endothermic engine.

According to the invention, the electric machine is located under the swingarm. This arrangement minimises the dynamic problems connected to the added mass of the electric machine, optimising motorcycle stability and riding safety.

According to a preferred embodiment of the invention, the electric machine is arranged basically symmetrically with respect to a vertical median plane of the motorcycle, which helps to optimise stability and safety.

According to a preferred embodiment of the invention, the electric machine can be selectively connected to the input shaft; in this way, in endothermic mode, it is possible to completely exclude the electric motor, avoiding the dragging of significant masses.

The electric machine is preferably counter-rotating with respect to the secondary transmission, so as to at least partially compensate for the gyroscopic effect of the wheels.

These and other advantages will be evident from the following description of a non-limiting embodiment of the invention, with reference to the attached drawings in which:.

With reference to <FIG>, the number <NUM> indicates, as a whole, a hybrid-drive motorcycle, in particular a motorbike, manufactured according to this invention.

The motorcycle <NUM> comprises, in a known way, a carrier structure <NUM> in which an endothermic engine <NUM> and a gearbox <NUM> are mounted or integrated (<FIG>). The carrier structure <NUM> may consist of a frame on which a crankcase housing the engine and the gearbox is mounted, of just the crankcase (in the case of a motorcycle with a load-bearing engine), or intermediate solutions comprising a crankcase and a partial frame.

The motorcycle <NUM> is, in addition, equipped with a front wheel <NUM> and a rear wheel <NUM>. The latter is attached to the carrier structure <NUM> by means of a swingarm <NUM>, which is hinged to the carrier structure <NUM> at its front end and carries the wheel <NUM> at its rear end.

The motorcycle (<FIG>) is equipped with a primary transmission <NUM>, e.g. with gears, which connects a drive shaft of the endothermic engine <NUM> to the gearbox <NUM>, and a secondary transmission <NUM>, e.g. by a chain, which connects an output shaft <NUM> of the gearbox <NUM> to the rear wheel <NUM>.

The output shaft <NUM> of the gearbox <NUM> is therefore the input shaft of the secondary transmission <NUM>.

The secondary transmission <NUM> may comprise, for example, a pinion <NUM> placed on the shaft <NUM>, a rear sprocket <NUM> attached to the rear wheel <NUM>, and a chain <NUM> engaging with the pinion <NUM> and the rear sprocket <NUM> (<FIG>).

Alternatively, the secondary transmission could be of any other known type, e.g. a toothed belt or drive shaft.

The motorcycle <NUM> also comprises an electric machine M that is permanently or selectively connected to the secondary transmission <NUM>, and, in particular, to the input shaft <NUM> of the same. The electric machine is preferably an axial-flow permanent magnet machine, with an external rotor, and is arranged with its own axis A perpendicular to a median longitudinal plane P of the vehicle.

According to a first embodiment of the invention, illustrated in <FIG>, the electric machine M is permanently connected to the input shaft <NUM> of the secondary transmission <NUM>, for example by means of an auxiliary chain transmission <NUM> comprising a pinion <NUM> connected to an output shaft <NUM> of the electric machine, a pinion <NUM> firmly connected to the output shaft of the gearbox <NUM> and a chain <NUM>. Alternatively, the auxiliary transmission <NUM> could be a gear or belt transmission.

According to another embodiment of this invention, schematically illustrated in <FIG>, the auxiliary transmission <NUM> comprises a reversing/decoupling unit <NUM> and a belt transmission <NUM> in series with each other.

More specifically, the reversing/decoupling unit <NUM> comprises a first toothed wheel <NUM> integral with the output shaft <NUM> of the electric machine M and a second toothed wheel <NUM> that can be selectively engaged with an idle shaft <NUM>.

Conveniently, the selective engagement of the toothed wheel <NUM> on the idle shaft <NUM> is implemented by means of a sliding sleeve <NUM> with front teeth, equipped with a synchroniser (not illustrated). The sleeve <NUM> acts as a decoupler for the electric machine M.

The belt transmission <NUM> comprises a first crown wheel <NUM> on the idle shaft <NUM> and a second crown wheel <NUM> rotationally connected to the output shaft <NUM> of the gearbox <NUM>.

According to this invention, the electric machine M is mounted on the carrier structure <NUM> below the swingarm <NUM>. It should be noted that the expression "below the swingarm <NUM>" is to be understood as meaning that at least the main part of the electric machine M and the axis A of the electric machine itself are located below the swingarm <NUM>; if not all the electric machine M is located below the swingarm <NUM>, the latter must be configured so as not to interfere with the overall dimensions of the electric machine M under static and dynamic conditions. For example, in the case of a two-arm swingarm, it is possible that a top portion of the electric machine M may be located at the same height as the swingarm <NUM> during at least part of its travel, in which case the transverse dimensions of the electric machine M must be located between the two arms of the swingarm <NUM>, so that no interference occurs.

The electric machine M is conveniently arranged symmetrically in relation to a vertical median plane P of the motorcycle <NUM> (<FIG>).

<FIG> illustrates a first embodiment of a support unit <NUM> for connecting the electric machine M to the carrier structure <NUM>.

The support unit <NUM> consists of a bracket comprising a top plate <NUM> designed to be arranged, in use, between the arms of the swingarm <NUM>, in the transverse direction, and between the carrier structure <NUM> and the rear wheel <NUM>, in the longitudinal direction. The top plate <NUM> is configured so that it can be fixed to the carrier structure <NUM> by means of screws and/or clamps, preferably using connection holes already existing in the structure itself (e.g. the swingarm <NUM> hinge holes). The unit <NUM> also comprises a pair of arms 42a, 42b extending downwards on opposite sides of the top plate <NUM> and arranged on axially opposite sides of the electric machine M.

One of the arms 42a is fixed to the stator of the electric machine M, the other arm 42b ends with a ring-shaped support <NUM> for the output shaft <NUM> of the electric machine M, within which the shaft <NUM> is supported by a bearing (not illustrated).

<FIG> illustrate a different embodiment in which the unit <NUM> is composed of two brackets <NUM>, <NUM> with respective top portions <NUM>, <NUM> designed to be fixed to the opposite sides of the carrier structure <NUM> of the motorcycle <NUM>, and for the purpose provided, with multiple fixing holes <NUM> each.

The brackets <NUM>, <NUM> also comprise respective arms <NUM>, <NUM> fixed to or integral with the top portions <NUM>, <NUM> and extending downwards from axially opposite sides of the electric machine M. In this case too, the arm <NUM> is fixed to the stator of the electric machine M; the arm <NUM> terminates in a ring-shaped support <NUM> for the output shaft <NUM> of the electric machine M, within which the shaft <NUM> is supported by means of a bearing (not illustrated).

This solution is suitable for situations where there is not enough space to install a bracket between the arms of the swingarm <NUM>, or where the swingarm is a single-arm one. The brackets <NUM>, <NUM> are conveniently shaped so that they can be arranged outside the swingarm <NUM>, defining enough space with the carrier structure <NUM> to enable the passage and vertical travel of the swingarm <NUM>. This solution has larger dimensions than the previous one but is more flexible and can be easily adapted to different motorcycle models, using attachment holes already present on the carrier structure. For example, the brackets <NUM>, <NUM> can replace the support brackets of the passenger pedals, and integrate the pedals themselves.

<FIG> illustrates a block diagram of the control of the electric machine M.

A microprocessor control unit <NUM> receives input signals from a number of on-board sensors, including - with reference to the functions concerned here - at least one lateral inclination or roll sensor <NUM>, one inclination or rearing sensor <NUM>, one front wheel <NUM> angular velocity sensor <NUM>, and one rear wheel <NUM> angular velocity sensor <NUM>.

The control unit <NUM> sends control signals to an inverter <NUM> joined to the electric machine M, which is connected to a battery pack <NUM> equipped with a management system (BMS) <NUM> that communicates with the control unit <NUM>. The inverter <NUM> is conveniently attached to a lower area of the carrier structure <NUM> and housed as low as possible, e.g. in front of the endothermic engine <NUM> (<FIG>). The battery pack <NUM> is conveniently fixed to the inside of a tail piece <NUM> of the motorcycle <NUM>, below the seat.

The control unit also receives an input signal from an accelerator <NUM> in the form of a potentiometer conventionally controlled by a knob on the handlebar.

The operation of the hybrid traction system of the motorcycle <NUM> is as follows.

The motorcycle <NUM> is conventionally driven by just the endothermic engine <NUM>.

If there is an decoupler <NUM>, the sleeve <NUM> is disengaged; the electric machine M is excluded from the kinematic chain, and only the belt transmission <NUM> is dragged idle, with negligible inertia.

Keeping the gearbox <NUM> in neutral, (and the sleeve <NUM> engaged, if present) the motorcycle is driven by just the electric machine M. The endothermic engine <NUM> is isolated and therefore does not introduce any inertia to the unwanted rotation. When braking, the electric machine is used as a regenerative brake to recharge the battery <NUM>.

In this mode, both the endothermic engine <NUM> and the electric machine M are used simultaneously, so that the sum of the driving power ("boost") or braking power can thus be obtained, depending on the position of the accelerator <NUM>. The control unit <NUM> distributes the torque between the endothermic engine <NUM> and the electric machine M on the basis of maps stored according to input signals, and in particular according to the speed, power demand, and load. In this case too, the electric machine M can be used as a regenerative brake to recharge the battery <NUM>.

In this mode, complex control strategies can be implemented in particular operating situations that are identified on the basis of input signals, such as the following:.

The torque distribution maps between the thermal engine <NUM> and the electric machine M can be modified according to the lateral inclination or roll angle of the motorcycle.

In particular, it may be configured so that the torque contribution of the electric machine cancels out at a value of the maximum permissible inclination angle, and increase progressively as the inclination angle decreases (i.e. when exiting a curve). The mapping can be performed using not only the inclination angle but also the speed as input parameter.

Lastly it is clear that modifications and variations may be made to the motorcycle described without thereby departing from the scope of protection as defined by the claims.

For example, the reversing/decoupling unit, if present, can be configured as a two-speed gearbox, in order to define a "short" gear, for obtaining a high breakaway torque in electric mode, and a "long" gear, to be used when the electric machine is used as a boost in combination with the endothermic engine.

According to an example not falling under the scope of the appended claims, the electric machine, the support unit, and its control and supply means (inverter and battery) can also be supplied separately as a hybridization kit that can be applied to a conventional motorcycle that only has a thermal engine. The kit may conveniently comprise an interchangeable tail piece with the original motorcycle tail piece, in which the battery is integrated.

Claim 1:
A hybrid-drive motorcycle comprising a carrier structure (<NUM>), an endothermic engine (<NUM>) mounted on or housed in the carrier structure (<NUM>), a front wheel (<NUM>), a rear wheel (<NUM>) connected to the carrier structure (<NUM>) through a swingarm (<NUM>), a gearbox (<NUM>) connected to the endothermic engine (<NUM>) through a primary transmission (<NUM>) and to the rear wheel (<NUM>) through a secondary transmission (<NUM>), and a reversible electric machine (M), an auxiliary transmission (<NUM>) connecting the electric machine (M) to an input shaft (<NUM>) of the secondary transmission (<NUM>), and a support unit (<NUM>) secured to the carrier structure (<NUM>), characterized in that the support unit (<NUM>) is configured to support the electric machine (M) below the swingarm (<NUM>).