Patent Description:
Reduction of automotive fuel consumption and emissions is an ongoing process that involves more and vehicles, including agricultural and work vehicles, powered either entirely or in hybrid fashion by electric machines.

In general, hybrid/electrified vehicles differ from conventional internal combustion powered motor vehicles in that they are powered, at least in part, by one or more electric machines.

Such electric machines occupy a significant space and may be arranged, if present, far from the internal combustion engine.

However, the re-arrangement of the elements of the axle in the transmission vehicle would mean to update globally the design of the vehicle thereby incurring in high costs.

Moreover, each agricultural vehicle configuration has different typology of gearbox and therefore each gearbox configuration would need a specific reconfiguration of the hybrid vehicle.

Therefore, the need is felt to provide a hybrid axle design whereby one or more electric motors are coupled to a drive axle of a vehicle that are reduces product complexity and cost-effective in order to optimize the space of installation.

<CIT> discloses a drive train comprising a hybrid transmission, in particular a dedicated hybrid transmission, having: a transmission input shaft which is or can be rotationally connected to an internal combustion engine; a transmission output shaft; and at least one transmission gear stage between the transmission input shaft and the transmission output shaft, said transmission gear stage being formed by a shiftable spur gear stage having a fixed gear and an idler gear. In order to increase driving comfort, according to the invention: the first electric machine is or can be rotationally connected to at least one fixed gear of the transmission output shaft via a first power path; and a second electric machine can be rotationally connected to at least one fixed gear of the input shaft via a second power path, or alternatively to a fixed gear of the transmission output shaft via a third power path.

<CIT> discloses a multi purpose vehicle comprising an all wheel drive hybrid powertrain and a front power take off.

An aim of the present invention is to satisfy the above mentioned needs in an optimized and cost-effective way.

The aforementioned aim is reached by a front hybrid driving axle as claimed in independent claim <NUM> and a vehicle as claimed in claim <NUM>.

Preferred embodiments of the invention are realized according to the dependent claims.

<FIG> discloses a work vehicle <NUM> such as a tractor provided with a front axle <NUM> and a rear axle <NUM> that are movable with respect to the ground thanks, e.g. to wheels <NUM>.

The vehicle <NUM> is provided with an internal combustion engine <NUM> and a rear transmission module <NUM> that is operatively interposed between the internal combustion engine <NUM> and the rear axle <NUM>.

According to the invention, the front axle <NUM> is a hybrid driving axle, as described in the following, that is operatively connected to a plurality of electric machines <NUM>, to the internal combustion engine <NUM> and to rear transmission module <NUM>.

Making reference to <FIG>, <FIG> and <FIG> the hybrid axle <NUM> comprises a housing <NUM> that is configured to be fixed to the housing of internal combustion engine <NUM>. In particular, the housing <NUM> defines a plurality of openings <NUM> configured to house fixing means, not shown, such as threaded elements to fix the housing to the internal combustion engine <NUM>.

In particular, such openings <NUM> are realized about axes that are parallel to a longitudinal axis A of the internal combustion engine <NUM>, i.e. an axis that is parallel to an output shaft <NUM> of the internal combustion engine <NUM>. More preferably, the housing <NUM> extends transversally to axis A similarly to the internal combustion engine <NUM>, thereby defining together the same transversal encumbrance.

Advantageously, the housing <NUM> is furthermore connected to internal combustion engine <NUM> via a pair of lateral arms <NUM>, namely a right and a left arm with respect to axis A. As better shown in <FIG>, each arm <NUM> defines an inner portion 11a coupled to internal combustion engine <NUM> and an outer portion 11b coupled to the housing <NUM>.

In greater detail, the inner portion 11a defines at least one opening that allows the fixation of the inner portion 11a to the housing <NUM>.

Preferably, lateral arms <NUM> are connected together via a transversal member <NUM> that is substantially at the same height of the bottom of the housing <NUM>. More preferably, the inner and outer portions 11a, 11b are positioned at a different height, i.e. the outer portion 11b is positioned near the bottom of the housing <NUM>, i.e. near the transversal member <NUM>, while the inner portion 11a is positioned on the internal combustion engine at a greater height. Accordingly, they are inclined and, preferably, in the described embodiment, curved with the convex portion faced to ground.

Moreover, the housing <NUM> may be realized in two portions, namely an inner portion 7a that is faced to the internal combustion engine <NUM> and an outer portion 7b connected to the inner portion 7a on the opposite side with respect to internal combustion engine <NUM>.

Housing <NUM> defines support points <NUM> for allowing the connection of suspension elements <NUM> configured to support a wheel hub <NUM> of the axle <NUM>. In the disclosed embodiment both portions 7a, 7b defines support points <NUM> and the wheel hub <NUM> is carried in suspended way but it is clear that may be directly connected, e.g. via a fixed connection element, to at least one of portions 7a, 7b of housing <NUM>.

Housing <NUM> may furthermore define a further support point <NUM>. In the disclosed embodiments, such support point <NUM> is carried by housing 7a substantially along axis A. Support point <NUM> is configured to allow the connection of a front lifting system actuator, not shown, and may be realized via a pair of parallel flanges integrated in housing 7a.

According to the embodiment shown in <FIG>, <FIG> and <FIG> the housing <NUM> defines an inner space <NUM> configured to house at least a pair of electric machines <NUM>. According the alternative embodiment of <FIG>, the housing <NUM> is not shaped so that the inner space <NUM> may contain the electric machines <NUM>, i.e. electric machines <NUM> are coupled to the housing <NUM> but not integrated therein.

The electric machines <NUM> are electrically connected one with respect to the other. In particular, the axle <NUM> further comprises electronic control means <NUM>, such as inverters <NUM>, configured to electrically connect and control the operation of the electric machines <NUM>. In the embodiment of <FIG>,<FIG> and <FIG> such electronic control means <NUM> are integrated to the housing <NUM>, while in the embodiment of <FIG> they are realized as separate elements fixed to the housing <NUM>.

It may be appreciated that in both embodiments the electric machines <NUM> and electronic control means <NUM> are placed on the opposite of the internal combustion engine <NUM>, i.e. integrated or fixed to the outer portion 7b of housing <NUM>.

Clearly, the electric machines <NUM> and electronic control means <NUM> are electrically connected together. Such electric connection maybe realized via usual electric cables or, more advantageous, by means of specific power bars. In the embodiment of <FIG>, wherein the electric machines <NUM> and electronic control means <NUM> are integrated into housing <NUM>, such cables/power bars are all housed in inner space <NUM>, and fixed to the latter according the specific design requested by the technology".

Furthermore, is noticed that inner portion 7a of housing <NUM> has vertically a lower extension with respect to outer portion 7b thereby allowing the fixation of cooling means <NUM> for cooling the internal combustion engine <NUM> (shown only in the embodiment of <FIG> for sake of clarity).

The front axle <NUM> may further comprises protection cover <NUM> placed on outer portion 7b for protecting a Front Power Take-Off, FPTO, <NUM>.

As said, the front axle <NUM> is operatively connected to internal combustion engine <NUM>, rear transmission <NUM> and electric machines <NUM>. Such connection is achieved via transmission group <NUM> that is housed in inner space <NUM>. If present, also FPTO <NUM> is operatively connected to such transmission group <NUM>.

In particular, the transmission group <NUM> is operatively connected to internal combustion engine <NUM> via coupling means <NUM> such as a clutch <NUM> that is operatively interposed between the output shaft <NUM> of internal combustion engine <NUM> and a first shaft <NUM> of the transmission group <NUM>. The transmission group <NUM> is operatively connected to rear transmission arrangement <NUM> via a shaft, e.g. a jackshaft <NUM>, that is configured to be coupled to a second shaft <NUM> of the transmission group <NUM> and to transfer the torque provided by output shaft <NUM> to an output shaft <NUM> of the rear transmission arrangement <NUM>.

In greater detail, as appreciated in <FIG> and <FIG>, the jackshaft <NUM> is arranged between lateral arms <NUM> and above transversal member <NUM> and extends, parallel to axis A, over underneath the internal combustion engine <NUM> to transmission <NUM>.

Making reference to <FIG>, the transmission group <NUM> in detail comprises a first electric machine 18a selectively coupled to internal combustion engine <NUM> via coupling means <NUM> and a second electric machine 18b coupled via a third shaft <NUM> to output shaft <NUM>.

In detail, the first electric machine 18a may be provided with an output shaft <NUM>' that carries, in a rotatably free manner, a first output gear wheel <NUM> that may be engaged in rotation to output shaft <NUM>' thanks to a selector <NUM>, such as a dog clutch that can be actuated thanks to an actuator <NUM> such as an electro-mechanic actuator.

The first output gear wheel <NUM> is configured to cooperate with a first intermediate gear wheel <NUM> that is carried, engaged at rotation, with the first shaft <NUM> of the transmission group <NUM>.

The second electric machine 18b may be provided with an output shaft <NUM>'' that carries, engaged at rotation, a second output gear wheel <NUM>, engaged in rotation to output shaft <NUM>" and configured to mesh with a second intermediate gear wheel <NUM> that is carried by the third shaft <NUM>.

The third shaft <NUM> carries at least a wheel <NUM> configured to mesh with a corresponding gear <NUM> carried by second shaft <NUM>. In the disclosed embodiment, the second shaft <NUM> carries three gear wheels <NUM>', <NUM>'', <NUM>‴ configured to alternatively mesh with respective gear wheels <NUM>', <NUM>'', <NUM>‴ carried by the third shaft <NUM>. In particular, the previously mentioned gears have different diameters thereby engaging defining three different gear ratios between the second and third shafts <NUM>, <NUM>. The choice between a specific gear ratio may be achieved via a selector <NUM> controlled by an actuator <NUM> as previously described.

Exempli gratia, a first gear wheel <NUM>' of the third shaft <NUM> may be carried engaged in rotation therewith and the second and third gear wheels <NUM>", <NUM>'' of the second shaft <NUM> may be carried engaged in rotation therewith. The corresponding gears, i.e. the first wheel <NUM>' carried by the second shaft <NUM> and the second and third gear wheels <NUM>", <NUM>‴ carried by the third shaft <NUM> may be carried in a rotationally free manner. As represented for sake of example, a selector <NUM> may be placed near gear <NUM>' and a further selector <NUM> may be placed between gears <NUM>", <NUM>‴.

The second shaft <NUM> carries a further gear <NUM> rotationally engaged therewith and configured to mesh with a gear <NUM> that is rotatably engaged with a fourth shaft <NUM>.

The fourth shaft <NUM> engages with a front differential assembly <NUM> configured to split the torque between the wheel hubs <NUM>, as per se known and with the jackshaft <NUM>.

The jackshaft <NUM> is connected to a fifth shaft <NUM> that carries, engaged at rotation, a gear wheel <NUM> that is configured to mesh with a gear wheel <NUM> carried, in a rotationally free manner by rear transmission shaft <NUM>. The gear wheel <NUM> can be engaged at rotation with rear transmission shaft <NUM> thanks to coupling means <NUM> such as a dog clutch <NUM>.

As said, the front axle <NUM> may be provided with a FPTO <NUM>. In such case, the first shaft <NUM> carries, engaged at rotation therewith, a further gear <NUM> configured to mesh with a corresponding gear <NUM> carried by a sixth shaft <NUM>. Preferably, the gears <NUM> and <NUM> may mesh thanks to the presence of an intermediate gear <NUM> carried in rotation by an intermediate shaft <NUM>.

The sixth shaft <NUM> is operatively coupled to a FPTO shaft <NUM>. Preferably, the sixth shaft <NUM> carries at least a wheel <NUM> configured to mesh with a corresponding gear <NUM> carried by FPTO shaft <NUM>. In the disclosed embodiment, the sixth shaft <NUM> carries two gear wheels <NUM>', <NUM>" configured to alternatively mesh with respective gear wheels <NUM>', <NUM>" carried by the FPTO shaft <NUM>.

In particular, the previously mentioned gears have different diameters thereby engaging defining two different gear ratios between the sixth and FPTO shafts <NUM>, <NUM>. The choice between a specific gear ratio may be achieved via a selector <NUM> controlled by an actuator <NUM> as previously described. In particular, selector <NUM> is interposed between gears <NUM>', <NUM>'' that are rotatably free carried on FPTO shaft <NUM> while gears <NUM>', <NUM>'' are rotatably engaged with sixth shaft <NUM>.

As can be seen in <FIG> and <FIG> the electric machines 18a, 18b are placed over the transmission group <NUM> between the FPTO <NUM> and the differential assembly <NUM> and, furthermore, they are placed symmetrically with respect to axis A and at the same height.

In particular, it is noticed that electric machines 18a, 18b comprises respective rotors 18a', 18b' that are coupled to the respective output shaft <NUM>', <NUM>'' and respective stators 18a", 18b'' that are rigidly carried internally with respect to outer portion 7b of housing <NUM>.

In particular, they are housed in a specific non structural inner housing (not shown) positioned in space <NUM> and carried to housing <NUM> in order to decrease the transmission of axle loads to electric machines <NUM>. This housing is furthermore configured to house the aforementioned cables and a cooling system (not shown) for the electric machines, according the needs of the electric machines.

All the shafts that are included in the transmission group <NUM> are parallel one with respect to the other and with respect to axis A. Consequently, the axis of the electric machines <NUM> are parallel to the axis of the shafts of the transmission group <NUM>.

Clearly, the transmission group <NUM> further comprises other mechanical elements such as bearings, shoulders, O-rings and other known mechanical elements used for mounting the above mentioned structure of gears and shafts comprises by the transmission group <NUM>.

The operation of the hybrid driving axle <NUM> according to the invention described above is the following.

Generally, the internal combustion engine <NUM> carries in rotation the shaft <NUM> and, on the opposite side and as known, the transmission <NUM> that provides torque to the rear transmission shaft <NUM> according to the ratio necessity of the vehicle. For sake of example, transmission <NUM> may be realized as described in <CIT>.

On the opposite side when the coupling means <NUM> couple together shafts <NUM> and <NUM> and when the selector <NUM> couples shaft <NUM>' to gear <NUM> the torque passes via gearings <NUM> and <NUM> to the first electric machine 18a. This latter may therefore work as generator, i.e. receiving mechanical energy and providing electrical energy.

In particular, such electrical energy may be used by the second electric machine 18b (or stored for further use) that provides torque to shaft <NUM>". The torque passes via gearing between gears <NUM> and <NUM> to shaft <NUM>. There, the user may select one gear ratio between the one defined by the coupling of gears <NUM>' and <NUM>' or <NUM>'' and <NUM>" or <NUM>‴ and <NUM>'''. The torque then passes through the selected gear ratio to shaft <NUM> and via meshing of gears <NUM> and <NUM> to shaft <NUM>.

This latter is connected to front differential <NUM>, that provides torque to the front axles of the axle <NUM> and to jackshaft <NUM>.

If the users selects a four drive wheels modality, the coupling means <NUM> may allow the engagement of wheel <NUM> with rear transmission shaft <NUM> thereby allowing torque transmission from jackshaft <NUM> to rear transmission shaft. In such case the torque provided by the jackshaft <NUM> is summed to the torque provided by the transmission <NUM>. In case the transmission <NUM> is not engaged, the vehicle <NUM> will be provided with a totally electric four-drive traction thanks to the above configuration.

If the FPTO <NUM> is present, it is possible to foresee two different operational conditions.

In a first possible operative condition, it may be assumed, as described above, that the engine shaft <NUM> is coupled to shaft <NUM> and that the selector <NUM> couples shaft <NUM>' to wheel <NUM>. In such configuration the torque provided by shaft <NUM> is divided between the first electric machine 18a, as described above, and, via meshing of gears <NUM>, <NUM> and <NUM> to shat <NUM>. By selecting a proper gear ratio between the gear couplings <NUM>' and <NUM>' or <NUM>'' and <NUM>", it is possible to vary the torque provided to FPTO shaft <NUM>. If the selector <NUM> does not couple shaft <NUM>' to wheel <NUM>, the entire torque provided by engine shaft <NUM> is directed towards the FPT shaft <NUM> because gear <NUM> rotates freely on shaft <NUM>'.

In a second possible operative condition, it may be assumed that the shaft <NUM> is not coupled to shaft <NUM>. Accordingly, only electric machine 18a, that in such case works as electric motor may provide torque via gears <NUM>, that is engaged to shaft <NUM>', and <NUM>, the gearings defined by wheels <NUM>, <NUM> and <NUM> and via one of the ratio defined by gear couplings <NUM>' and <NUM>' or <NUM>'' and <NUM>".

In such operative condition, the electrical energy to first electric machine 18a is provided by battery means or may be provided by second electric machine 18b that works as generator carried by torque arriving from rear transmission shaft <NUM> via jackshaft <NUM>.

In view of the foregoing, the advantages of the transmission group, the front hybrid driving axle according to the invention and vehicle comprising this latter are apparent.

The provided front hybrid driving axle has a very compact and small dimension, thereby allowing the use in substitution of existing standard axles.

Moreover, as shown, the front hybrid driving axle may be used both in conventional arrangement with respect to front hub wheels or in an independent suspended way.

Furthermore, electrical elements may be housed separately of integrated into the housing of the front hybrid driving axle thereby protecting this latter from the vehicle environment. Such latter solution is clearly more simple and safe.

In a very small space the front hybrid driving axle comprises the gearings to define the FPTO, the front differential and the transmission between the electrical motor and the rear transmission.

Such compact transmission group arrangement has very few elements with respect to existing one. Moreover, the compactness in a very small space allow a good lubrication with a small amount of lubricant.

In the use of electrical actuators, the actuation of the transmission elements is very rapid and has low power absorption.

It is clear, furthermore, that it is possible to have an independent traction on the front axle with respect to the rear axle or, alternatively, a four driving wheel traction or, further, a standard rear traction, according to the need of the agricultural vehicle.

As demonstrated, according to the capacity of the battery provided in the vehicle, it is possible to move the agricultural vehicle <NUM> in a full electric configuration.

The configuration with electric motors carried by housing but separated thereof allows to reduce the load stresses that may be provided to these latter.

It is clear that modifications can be made to the described transmission group, front hybrid driving axle according to the invention and vehicle comprising this latter which do not extend beyond the scope of protection defined by the claims.

For example, it is clear, as said, that the wheel hubs <NUM> may be fixedly carried to the housing <NUM> instead of the suspended configuration disclosed in the present application.

Furthermore, the disclosed geometries and dimension are variable according to the typology of agricultural vehicle.

Moreover the disclosed gears and gearings may vary according to the necessity of the work vehicle, in particular gear wheels may be of any typology and vary in number. Similarly shaft may be disposed in a different way and vary in their number.

Clearly, it is possible to foresee more than two electric machines and their relative position may vary with respect to the transmission group elements. Moreover, as shown, the electric machines may be integrated, or separated, with respect to housing of the hybrid driving axle.

Claim 1:
Front hybrid driving axle (<NUM>) for an agricultural vehicle (<NUM>), said axle (<NUM>) comprising a housing (<NUM>) configured to define an inner space (<NUM>) configured to house transmission group (<NUM>), said axle (<NUM>) further comprising at least a pair of electric machines (<NUM>) and a differential assembly (<NUM>),
said transmission group (<NUM>) being operatively interposed between said at least a pair of electric machines (<NUM>),said differential assembly (<NUM>) and an internal combustion engine (<NUM>) of said vehicle (<NUM>),
wherein said transmission group (<NUM>) comprises a first shaft (<NUM>) configured to be selectively connected to an output shaft (<NUM>) of said internal combustion engine (<NUM>), said first shaft (<NUM>) being further selectively connectable to one (18a) of said pair of electric machines (<NUM>),
wherein said transmission group (<NUM>) comprises a second shaft (<NUM>) that is operatively connected to the other (18b) of said electric machines (<NUM>) and said differential assembly (<NUM>) ;
wherein said first shaft (<NUM>) is selectively connectable with a third shaft (<NUM>) that is coupled to a front power take off (<NUM>) of said vehicle.