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.

An example of a driving axle of the type mentioned above is described in <CIT>, which relates to a front hybrid driving axle for a vehicle provided with a housing which is adapted to be connected, at one end an internal combustion engine and at the other hand to an electric machine and lodges the transmission elements devoted to the transmission of the torque provided by internal combustion engine and electric machine to the ground engaging wheels.

<CIT> discloses then a front hybrid driving axle comprising: a housing configured to be fixed to an internal combustion engine; an electric machine carried by said housing wherein said housing comprises a front portion and a rear portion, said front portion comprising a front terminal portion and a rear terminal portion configured to be connected together to define a closed space for housing at least one transmission operatively connecting said electric machine and an engine shaft of said internal combustion engine, said front portion further comprising an intermediate portion and rear terminal portions and configured to divide said space in a first portion and a second portion, said intermediate portion being configured to support said at least one transmission within said space, wherein the rear terminal portion of said front portion further defines a first opening configured to allow the passage of an engine shaft and a second opening configured to allow the passage of a connection shaft.

A similar arrangement is disclosed in document <CIT>.

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.

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 as in claim <NUM> and an agricultural vehicle as in claim <NUM>.

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, therefore the PTO transmission <NUM> could be removed by the gearings comprised by housing <NUM> without interfering with the operation of electric path transmission <NUM>.

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>'' define 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 connection element <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>.

In particular, making reference to <FIG>, <FIG>, <FIG> and <FIG> it is noticed that the intermediate plate 7c' provide support for both the PTO transmission <NUM> and the electric path transmission <NUM>.

In detail, the intermediate plate 7c' defines three through openings <NUM>, <NUM>, <NUM> that extending along a common vertical axis B perpendicular to longitudinal axis A and therefore positioned in a substantially centered position in a transversal direction of the intermediate plate 7c'.

The openings <NUM>, <NUM>, <NUM> are configured to house, respectively, the shaft <NUM>, <NUM> and <NUM>. Accordingly, shaft <NUM>, <NUM> and <NUM> are placed in parallel with respect to longitudinal axis A and, in detail, the engine shaft <NUM> is vertically above the shaft <NUM> that is vertically above the connection shaft <NUM>.

The electric machines M', M'' are positioned along the transversal direction, i.e. along an axis C that is perpendicular to vertical and longitudinal axis A, B and preferably collinear.

In detail, it is noticed that the gearings connected to the first electric machines M' and the gearings connected to the second electric machines M'' are centered in points that belong to two different quadrants when considering the Cartesian plane defined by axis B and C.

As best shown in <FIG>, the PTO shaft <NUM> is collinear with shaft <NUM>. In particular, the PTO shaft <NUM> is housed, in an inner extremity, in a seat <NUM> defined by the shaft <NUM> in a rotatably free manner with respect to this latter.

As can be seen in <FIG>, the electric path transmission <NUM> is mainly coplanar to a plane P', i.e. the center of the gears connected to the first and second electric machines are comprise by a plane P'. Since in the present embodiment two reductor modules <NUM>', <NUM>" are present, the gears are disposed along two planes P', P'' one parallel with respect to the other and with respect to the intermediate portion 7c', i.e. perpendicular to longitudinal axis A, and spaced one with respect to the other along longitudinal axis A.

Similarly, the PTO transmission <NUM> is mainly coplanar to a plane R', i.e. the center of the gears connected to the PTO shaft are comprise by a plane R'. Since in the present embodiment two reductor modules <NUM>', <NUM>'' are present, the gears are disposed along two planes R', R'' one parallel with respect to the other and with respect to the intermediate portion 7c', i.e. perpendicular to longitudinal axis A, and spaced one with respect to the other along longitudinal axis A.

Furthermore, it is noticed that advantageously, planes P', P", R', R" are all parallel one with respect to the other.

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 reductor 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.

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.

Furthermore, the presence of the intermediate portion 7c' provides a unified support for the PTO transmission <NUM> and the electric path transmission <NUM>.

In detail, the intermediate portion 7c' provided two portion of inner space <NUM> that are closed and delimited and connected by suitable lubrication openings realized through this latter to improve lubrication.

Moreover, the proposed disposition provides at the same time enough space to correctly allow the mounting of the different gears in a way so that both the PTO transmission <NUM> and the electric path transmission <NUM> are independent. Furthermore, in the electric path transmission <NUM>, also the gears connected to the first electric machine M' are independently mounted with respect to the gears connected to the second electric machine M'', thereby providing, with the same intermediate portion 7c' support to different possible configurations of the hybrid driving front axle <NUM>.

Furthermore, the gearings are all compacted along longitudinal axis A in one or two planes P', P", R', R" thereby providing a very longitudinal compact assembly. Moreover, the assembly of the different portions of the transmission portions are facilitated and therefore quicker.

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>);
a plurality of electric machines (M', M") housed within 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>') comprising a front terminal portion (7a') and a rear terminal portion (7b') configured to be connected together to define a closed space (<NUM>) for housing at least one transmission (<NUM>, <NUM>) each comprising a plurality of gears and shafts housed within space (<NUM>), said at least one transmission (<NUM>, <NUM>) operatively connecting at least one of said plurality of electric machines (M', M") and an engine shaft (<NUM>) of said internal combustion engine (<NUM>),
said front portion (<NUM>) further comprising an intermediate portion (7c') longitudinally interposed between said front and rear terminal portions (7a', 7b') and configured to divide said closed space (<NUM>) in a first portion (<NUM>') and a second portion (<NUM>"),
said intermediate portion (7c') being configured to support said at least one transmission (<NUM>, <NUM>) within said closed space (<NUM>) );
wherein the rear terminal portion (7b') of said front portion (<NUM>') defines:
• a first opening (<NUM>) configured to allow the passage of an engine shaft (<NUM>) of said internal combustion engine (<NUM>),
• a second opening (<NUM>) configured to allow the passage of a connection shaft (<NUM>) that is operatively connected to one of said plurality of electric machines (M', M"), and
at least a pair of seats (<NUM>), which are each provided with an opening (<NUM>) each configured to house at least one of said plurality of electric machines (M', M").