Patent Description:
Reduction of automotive fuel consumption and emissions is an ongoing process that involves more and more 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 battery powered electric machines.

Such battery powered 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 vehicle would mean to update globally the design of the vehicle thereby incurring in high costs.

Moreover, each agricultural vehicle configuration has different power size and therefore each configuration would need a specific reconfiguration of the axle.

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 simple and cost-effective.

<CIT> and <CIT> disclose different examples of hybrid architecture for a compact layout.

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 hybrid driving front axle arrangement and a vehicle as claimed in the appended independent claims.

Preferred embodiments of the invention are realized according to the claims dependent on or related to the above independent claim.

<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, not shown.

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 M', M", to the internal combustion engine <NUM> and to rear transmission module <NUM>.

In particular, electric machines M', M" are electrically connected one with the other in order to allow electrical energy transfer between them. The tractor <NUM> further comprise electrical energy storage means (not shown) and an electric control unit (not shown) electrically connected to electric machines M', M" to control their operation.

Referring to the accompanying figures, the hybrid axle <NUM> comprises a housing <NUM> that is configured to be fixed to the housing of internal combustion engine <NUM> to house the electric machines M', M" and to house a mechanical transmission as defined in the following. Furthermore, the housing <NUM> is configured to be connected to hub wheels <NUM>, preferably via suspension systems <NUM>.

The housing <NUM> essentially comprises a front portion <NUM>' and a rear portion <NUM>" configured to be assembled together via fixation means such as threaded elements.

In particular, making reference to <FIG> and <FIG>, the front portion <NUM>' is configured to define a space <NUM> suitable for housing a power take off, PTO, transmission <NUM> and an electric path transmission <NUM> and to define a plurality of fixation points for fixing different operational elements of the vehicle <NUM> as defined below.

In greater detail, the front portion <NUM>' comprises a front terminal portion 7a' and a rear terminal portion 7b' configured to be assembled together via fixation means, such as traded elements, to define the space <NUM> housings transmissions <NUM>, <NUM>.

Preferably, the front terminal portion 7a' and a rear terminal portion 7b' comprises an intermediate plate 7c' that is axially comprises along a longitudinal axis A of the vehicle <NUM> between the front and rear terminal portions 7a', 7b'.

The intermediate plate 7c' divide the space <NUM> into a front portion <NUM>' voted to house main part of the PTO transmission <NUM> and a rear portion <NUM>" voted to house main part of the electric path transmission <NUM>.

It is furthermore notice that the PTO transmission <NUM> and the electric path transmission <NUM> are independent one with respect to the other from an operational point of view.

The front terminal portion 7a' is designed to define at least one among the following features:.

Furthermore, the front terminal portion 7a' is designed to allow the fixation of a hydraulic actuation assembly <NUM> configured to control other operational elements of the vehicle.

It can be appreciated that the opening <NUM> is placed in a front wall and center with respect to the hitch system <NUM> that comprises preferably at least a pair of lower arms and an upper arm.

The fixation points <NUM> are preferably realized in an upper wall of the front terminal portion 7a'.

The rear terminal portion 7b' is designed to define:.

As best shown in <FIG>, the openings <NUM>, <NUM> are substantially collinear to a vertical axis crossing the longitudinal axis A, while the pair of seats <NUM> are placed on opposite sides with respect to the longitudinal axis A, preferably equally distance with respect to this latter. The seats <NUM> are furthermore placed in a vertical intermediate position with respect to openings <NUM>, <NUM>.

<FIG> discloses a schematic representation of the gearings comprised by driving front axle <NUM> and operatively interposed between the engine shaft <NUM>, the PTO shaft <NUM> and the connection shaft <NUM>.

As said, the gearings comprises two different transmissions, the PTO transmission <NUM> and the electric path transmission <NUM>.

The PTO transmission <NUM> comprises coupling means <NUM> such as a clutch operatively interposed between the engine shaft <NUM> and a first intermediate shaft <NUM>. The PTO transmission <NUM> further comprises a reduction stage <NUM> operatively interposed between the first intermediate shaft <NUM> and the output shaft <NUM>; in particular, the reduction stage <NUM> may comprise two different reduction stages <NUM>', <NUM>" and selector means <NUM> configured to select alternatively the reduction stages <NUM>', <NUM>''. Such reduction stages <NUM>', <NUM>" being configured to vary the torque/speed provided by the engine shaft <NUM> with two different gear ratios.

In particular, the first reduction stage <NUM>' comprises a first wheel <NUM>' carried, preferably fixedly carried by shaft <NUM> and a second wheel <NUM>'' preferably carried in a rotatably free manner by PTO shaft <NUM>, while the second reduction stage <NUM>" comprises a first wheel <NUM>' carried, preferably fixedly carried by shaft <NUM> and a second wheel <NUM>'' preferably carried in a rotatably free manner by PTO shaft <NUM>.

The electric path transmission <NUM> preferably comprises a first wheel <NUM>' preferably carried in a movable manner by engine shaft <NUM> and configured to be selectively fixed to this latter by selection means <NUM>. Such first wheel <NUM>' is configured to be connected to an operative shaft of the first electric machine M, acting as generator, in particular thanks to a reduction stage <NUM>.

The reduction stage <NUM> preferably comprises a second shaft <NUM> provided with a first wheel <NUM>'' configured to mesh with the first wheel <NUM>' and a second wheel <NUM>'. Both the first and second wheels <NUM>" and <NUM>' are preferably carried in a fixed manner by second shaft <NUM>. The second wheel <NUM>' is configured to mesh with a third wheel <NUM>'' carried by the operative shaft of the electric machine M.

The electric path transmission <NUM> further comprises a reduction stage <NUM> operatively interposed between the second electric machine M', acting as motor, and the connection shaft <NUM>.

In particular, the reduction module <NUM> preferably comprises a third shaft <NUM> that is operatively interposed between the second electric machine M' and the connection shaft <NUM> and a first wheel <NUM>' carried by the operative shaft of the second electric machine M' and a second wheel <NUM>'' carried by the third shaft <NUM>, preferably in a fixedly manner.

The reduction module <NUM> further comprises a third wheel <NUM>' that is operatively connected to the connection shaft <NUM> preferably via a reduction stage <NUM>, in particular the reduction stage <NUM> may comprise two reduction stages <NUM>', <NUM>" and selector means <NUM> configured to select alternatively the reduction stages <NUM>', <NUM>''. Such reduction stages <NUM>', <NUM>'' being configured to vary the torque/speed provided by the gear <NUM> with two different gear ratios.

In particular, the first reduction stage <NUM>' comprises a first wheel <NUM>' carried, preferably fixedly carried by a first shaft <NUM> and a second wheel <NUM>'' preferably carried in a rotatably free manner by connection shaft <NUM>, while the second reduction stage <NUM>" comprises a first wheel <NUM>' carried, preferably fixedly carried by third shaft <NUM> and a second wheel <NUM>'' preferably carried in a rotatably free manner by connection shaft <NUM>.

The connection shaft <NUM> is then configured to mesh into a gearing device <NUM> that is operatively interposed between the connection shaft <NUM> and a rear transmission shaft <NUM> coming from the rear transmission module <NUM>. The gearing device <NUM> is configured to provide an output shaft <NUM> to provide torque to hub wheels <NUM>.

The above selector means <NUM> are schematized as dog clutches but may comprise any suitable selection means actuated in a mechanic, pneumatic or hydraulic way.

Coming back to the rear portion <NUM>'', as shown in <FIG>, it comprises a front terminal portion 7a'' and a rear terminal portion 7b'' that are preferably realized as one piece.

The rear terminal portion 7b" defines a closed space (not shown) configured to house gearing device <NUM> and openings <NUM> configured to allow the passage of output driving shafts <NUM> configured to be connected to the respective wheel hubs <NUM> to provide torque to these latter.

The front terminal portion 7a' ' defines an open space <NUM> configured to house a portion of the electric machines M', M". Accordingly, the space <NUM> is preferably laterally defined by curved walls that follows the profile of the electric machines M', M".

The space <NUM> is furthermore configured to house the connection shaft <NUM> that pass within the rear terminal portion 7b''.

Referring back to suspension systems <NUM>, the rear terminal portion <NUM>" defines connection points for fixing the different elements comprised by the suspension systems <NUM>.

In particular, the suspension systems <NUM> according to the shown embodiment comprise a lower and an upper connection elements <NUM> shaped as a fork, i.e. "Y"-shaped comprising an outer portion <NUM>' connected to the wheel hub and a pair of inner portions <NUM>'' extending longitudinally spaced along axis A with respect to outer portion <NUM>'.

In the described embodiment, the inner portions <NUM>'' are in particular curved defining a concave portion towards the housing <NUM>; furthermore, preferably both the inner and outer portions <NUM>'', <NUM>' have a curved shape defining a convex edge towards ground.

The outer portion <NUM>' is connected via a hinge <NUM> to the wheel hub to allow a rotation of this latter about a vertical axis and the inner portions <NUM>" are connected via a respective hinge <NUM> to the rear portion <NUM>''. Hinges <NUM> are configured to allow rotation about an axis parallel to longitudinal axis A.

The shape of the connection element <NUM> allows the passage of the driving shaft <NUM> above this latter between the rear portion <NUM>" and the hub wheels.

The front axle assembly <NUM> further advantageously comprises steering means <NUM> interposed between the hub wheel <NUM> and the rear portion <NUM>" and configured to control steering angle of the respective hub wheel <NUM>.

The steering system <NUM> according to the present embodiment comprises a steering arm <NUM> hinged via a hinge <NUM> to the wheel hub <NUM> in a position distanced by the rotation axis of hinge <NUM>. Therefore, movement of steering arm <NUM> cause a rotation of wheel hub <NUM> about rotation axis of hinge <NUM>.

The suspension system <NUM> ma further comprise a dampening element <NUM> such as a hydraulic cylinder operatively interposed between the housing <NUM> and the lower connection element <NUM> and configured to dampen vertical motion of this latter.

Clearly, the hybrid driving front axle <NUM> further comprises other mechanical elements such as bearings, shoulders, O-rings and other known mechanical elements used for mounting the above mentioned elements and here not described for sake of brevity.

The operation of the hybrid driving front 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 axle assembly <NUM> according to the ratio necessity of the vehicle.

On the opposite side when the selector means <NUM> couple together shafts <NUM> and <NUM> the torque passes via gearings <NUM>', <NUM>", <NUM>', <NUM>" to the first electric machine M'. 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 M" (or stored for further use) that provides torque to gear <NUM>'. The torque passes via gearing between gears <NUM>', <NUM>'' and one between the redactor modules <NUM>', <NUM>'' to connection shaft <NUM>. There, the torque passes through the gearing device <NUM> to the wheel hubs <NUM> via driving shaft <NUM> providing a front driving wheel configuration.

If no torque is provided by rear transmission shaft <NUM>, then the hubs <NUM> will be carried only by torque provided by electric machine M'', conversely, a four driving wheel configuration will be provided.

Clearly, if the selector means <NUM> does not engage engine shaft <NUM> to the electric path assembly <NUM>, this portion will not carried by thermal engine <NUM> and, in case, torque provided by rear transmission shaft <NUM> will pass to hubs <NUM> providing a standard rear driving wheel configuration.

In case, if one of selection means <NUM> engage one of reduction stages <NUM>', <NUM>'' to the connection shaft <NUM> when it is carried by the rear transmission shaft <NUM>, the torque will pass towards gear <NUM>' thereby allowing electric machine M" to act as a generator.

If the PTO transmission <NUM> is present, then, the PTO shaft <NUM> operation can be modulated by coupling means <NUM> that engage shaft <NUM> with the engine shaft <NUM>. In this way torque will pass from engine shaft <NUM> towards shaft <NUM> and then via reduction stages <NUM>', <NUM>'' to PTO shaft <NUM>.

In all the aforementioned operations reduction stages <NUM>', <NUM>", <NUM>', <NUM>" can be selected via selection means <NUM> by the user to provide a suitable output speed of the chosen functionality.

In view of the foregoing, the advantages of 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, the proposed housing allows to provide possible fixation points for many different elements of the tractor <NUM> in a compact and optimized way. Accordingly, the same housing <NUM> may be used for many different combination of element configuration that may be provided to the user.

Therefore, manufacturing costs are reduced and versatility of the proposed front hybrid driving axle is increased.

Furthermore, electrical elements are housed within a dedicated space in 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 of the PTO and of the electric path. Furthermore, such gearings are provided in a closed and lubricated space that increases their useful life.

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.

It is clear that modifications can be made to the described 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 instance, 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.

Claim 1:
Front hybrid driving axle (<NUM>) for an agricultural vehicle (<NUM>), said front hybrid driving axle (<NUM>) comprising:
a housing (<NUM>) configured to be fixed to an internal combustion engine (<NUM>) of said agricultural vehicle (<NUM>);
at least one electric machine (M', M") carried by said housing (<NUM>);
wherein said housing (<NUM>) comprises a front portion (<NUM>') and a rear portion (<NUM>") configured to be connected together along a longitudinal axis (A) of said vehicle (<NUM>),
said front portion (<NUM>') defining a closed space (<NUM>) for housing at least one transmission (<NUM>, <NUM>) each comprising a plurality of gears and shafts housed within said closed space (<NUM>), said at least one transmission (<NUM>, <NUM>) configured for operatively connecting said at least one electric machine (M', M") and an engine shaft (<NUM>) of said internal combustion engine (<NUM>);
said front hybrid driving axle (<NUM>) is characterized in that said front portion (<NUM>') is configured to carry said at least one electric machine (M', M") outside said closed space (<NUM>) and
said rear portion (<NUM>") is defining a space (<NUM>) for housing said at least one electric machine (M', M") and connection points for fixing respective wheel hubs (<NUM>) of said vehicle (<NUM>) .