Patent Description:
The ecological transition increasingly requires the use of electric motors to assist or replace internal combustion engines for the purposes of vehicular transport.

To this end, it is known to provide traction assemblies configured to provide torque to the wheels of a vehicle comprising, at the same time, a power take-off configured to connect to an output shaft of an internal combustion engine and one or more electric motors configured to cooperate with or replace this internal combustion engine.

It is required that these traction assemblies are compact and versatile, i.e., that they do not excessively increase the dimensions and weight of the vehicle but manage to provide various operating configurations. This requirement is felt more urgently in heavy vehicles, where it is necessary to provide torque to the wheels depending on the different vehicle operating needs.

<CIT> discloses a pertinent traction assembly.

Thus, the need is felt to provide traction assemblies that manage to be versatile and compact.

The object of this invention is to meet the above requirements in a cost-effective and optimised manner.

The above-mentioned purpose is achieved with a vehicle traction assembly as claimed in the attached claims.

For a better understanding of this invention, a preferred embodiment is described below by way of non-limiting example and with reference to the accompanying drawings, wherein:.

The reference number <NUM> indicates, in the attached figures, a traction assembly according to the invention configured to transmit torque to corresponding couplings <NUM>, <NUM> configured to be connected to a front axle (not illustrated) and a rear axle (not illustrated) of a vehicle, not illustrated, to transmit the torque received to the latter.

In particular, the traction assembly <NUM> is configured to provide torque to the couplings <NUM>, <NUM> starting from at least one of either: an input clutch <NUM> configured to be connected to a combustion engine (not illustrated) of the vehicle and at least one electric machine <NUM>, described, below, for brevity, as an electric motor, configured to provide torque using electricity, for example provided by a vehicle battery set (not illustrated) or to absorb torque to generate electricity to provide to this battery set.

The traction assembly <NUM> comprises a transmission <NUM> operationally placed between the couplings <NUM>, <NUM>, the input clutch <NUM> and the at least one electric motor <NUM> configured to enable the transmission of torque according to at least one speed ratio.

Advantageously, the traction assembly <NUM> comprises a casing <NUM> configured to delimit a space <NUM> that is isolated from the outside; the space <NUM> is configured to house the transmission <NUM> as described below. Preferably, the casing <NUM> comprises a central portion 7a and a pair of side portions 7b placed near the couplings <NUM>, <NUM>.

As illustrated in <FIG>, the transmission <NUM> comprises an input shaft <NUM> rotationally supported by the central portion 7a of the casing <NUM> via a pair of rolling supports <NUM> around an axis A and extending partially outside the casing <NUM>. The input clutch <NUM> basically comprises a connection plate <NUM> that can be connected to the internal combustion engine and to the shaft <NUM> as described below.

The transmission <NUM> comprises a differential assembly <NUM> that is operationally placed between the couplings <NUM>, <NUM> and the shaft <NUM>.

More precisely, the couplings <NUM>, <NUM> each comprise a plate 2a, 3a connecting with the respective axles and placed outside the casing <NUM>, in particular by the side portions 7b of the latter, and a hub 2b, 3b extending inside the casing <NUM> and rotationally supported on the side portion 7b of the latter via the rolling supports <NUM>.

In particular, the hubs 2b, 3b are coaxial between them around a rotation axis B that, preferably, is parallel to the rotation axis A of the shaft <NUM>.

The hubs 2b, 3b are configured to cooperate with the differential assembly <NUM> as described, in detail, below.

The differential assembly <NUM> may be, as illustrated, of a known type, i.e., comprising a chain carrier <NUM> carrying multiple planet gears <NUM>, for example four planet gears equally angularly spaced apart by <NUM>° and supported by a cross-shaped support <NUM> that is rigidly carried by the chain carrier <NUM> and around which arms can rotate the planet gears <NUM>. In particular, the planet gears rotate on the support <NUM> around axes contained on a plane perpendicular to the axis B.

The planet gears <NUM> cooperate with a corresponding crown wheel comprising, respectively, a conic, left toothed wheel 17a and a right toothed wheel 17b rigidly carried by corresponding support shafts 18a, 18b carried rotationally by the casing <NUM>, around the axis B and, thus, coaxially between them; advantageously, these support shafts 18a, 18b are supported rotationally freely by the central portion 7a using rolling supports <NUM>.

In particular, the differential assembly <NUM> is operationally connected to the shaft <NUM> via a reducer assembly <NUM> comprising a support shaft <NUM> carried rotationally freely by the casing <NUM> around an axis C using rolling supports <NUM>, in particular by the central portion 7a in a vertical position between the shaft <NUM> and the differential assembly <NUM>.

Specifically, the support shaft <NUM> defines a toothing <NUM> rigidly carried by the support shaft <NUM> and, preferably, advantageously made of a single piece with the same and supports a pair of toothed wheels <NUM>, <NUM>, in the example described placed to the side of the toothing <NUM>. The toothed wheels <NUM>, <NUM> are preferably carried, integral with the rotation, by the support shaft <NUM>.

The shaft <NUM> carries a pair of toothed wheels <NUM>, <NUM> configured to mesh with the toothed wheels <NUM>, <NUM> and, as a result of the above, carried rotationally freely around the axis A by the shaft <NUM>.

The transmission <NUM> comprises selector means <NUM> configured to make one of the toothed wheels <NUM>, <NUM> selectively integral with the shaft <NUM>.

Preferably, these selector means <NUM> comprise a sleeve <NUM> carried integral to the rotation but free in its translation on the axis A by the shaft <NUM>. In particular, the sleeve <NUM> defines a toothing <NUM> configured to cooperate with a toothing <NUM> made on the shaft <NUM>.

The toothed wheels <NUM>, <NUM> are each provided with a hub that defines respective portions equipped with toothings <NUM>, <NUM>. The sleeve <NUM> is sized so that, running along the axis A, it can mesh its toothing <NUM> with the toothing <NUM> of the shaft <NUM> and one of the toothings <NUM>, <NUM> of the toothed wheels <NUM>, <NUM>.

In particular, the selector means <NUM> comprise actuator means <NUM> configured to move the sleeve <NUM> along the shaft <NUM>. Advantageously, these actuator means <NUM> are pneumatic actuator means.

According to the embodiment described, these actuator means <NUM> preferably comprise a rod <NUM> carried rigidly by a shaft <NUM> equipped, at the respective ends, with pistons <NUM> free to move in chambers <NUM> at least one of which is configured to selectively house a pressurised fluid, for example compressed air.

As better illustrated in <FIG>, the actuator means <NUM> also comprise elastic means <NUM>, such as a helical spring <NUM>, operationally placed between the shaft <NUM> and the casing <NUM> so as to keep the sleeve <NUM> meshed with the toothed wheel <NUM> when there is no compressed fluid in one of the chambers <NUM>.

The toothing <NUM> of the support shaft <NUM> meshes with a toothing <NUM> carried integrally by the chain carrier <NUM> of the differential assembly <NUM>. In the embodiment described, the chain carrier <NUM> is divided into two axial portions, symmetrical with each other, and the toothing <NUM> is made on a circular crown fixed between the two axial portions of the chain carrier <NUM> via threaded connection means.

Referring to <FIG>, it should be noted that the transmission <NUM> comprises an additional input shaft <NUM> configured to be connected, integral with the rotation, to the output shaft of the electric motor <NUM> and supported rotationally freely, via rolling bodies <NUM>, by the casing <NUM>, in particular by the central part 7a of the same.

In particular, the shaft <NUM> is configured to support a pair of toothed wheels <NUM>, <NUM> configured to be operationally connected to the differential assembly <NUM>; as illustrated, they are connected to the toothed wheels <NUM>, <NUM>, like the wheels <NUM>, <NUM>, using a reduction stage <NUM>.

As illustrated, the toothed wheels <NUM>, <NUM> are supported rotationally freely on the shaft <NUM>. Similarly to what was described for the toothed wheels <NUM>, <NUM> on the shaft <NUM>, the transmission <NUM> comprises selector means <NUM> that are configured to make one of the toothed wheels <NUM>, <NUM> integral with the shaft <NUM>. Since the selector means <NUM> and the actuator means <NUM> are similar to those described above, i.e., the first configured to mesh with the toothings <NUM>, <NUM> made on the hub of the toothed wheels <NUM>, <NUM> under the action of the second, they will not be further described for brevity's sake.

It should be noted, in any case, how, in this case, as better seen in <FIG>, the shaft <NUM> is placed between the casing <NUM> using a pair of elastic means <NUM> exerting opposite forces to each other and, thus, maintaining the sleeve <NUM> in a rest position where it runs idly on the shaft <NUM>.

Recalling the couplings <NUM>, <NUM>, with reference to <FIG>, it should be noted how, preferably, the hub 2b of the coupling <NUM> is separated from the support shaft 18a while it should be noted how the hub 3b of the coupling <NUM> consists of a single piece with the support shaft 18b.

The transmission <NUM> comprises selector means <NUM> to select an integral traction of the vehicle, i.e., to enable the provision of output torque from the differential to both the couplings <NUM>, <NUM>.

According to the above, the selector means <NUM> are configured to connect the hub 2b of the coupling <NUM> to the support shaft 18a. In particular, the selector means <NUM> comprise a sleeve <NUM> equipped with corresponding toothings <NUM>, <NUM> made on axially opposite sides to each other along the axis B.

The sleeve <NUM> is supported, integral in rotation but free to run along the axis B, for example via a grooved coupling, on the support shaft 18a and is configured to assume a first position in which the toothing <NUM> cooperates with another toothing <NUM> carried rigidly by the hub 2b and a second position in which the toothing <NUM> cooperates with a toothing <NUM> that is rigidly carried by the support shaft 18a.

The sleeve <NUM> is controlled via actuator means <NUM> controlling the selection of the sleeve <NUM> similarly to the selection of the toothed wheels <NUM>, <NUM> and, thus, not further described for brevity's sake. In particular, the elastic means <NUM> keep the sleeve in a rest condition so that the toothings <NUM> and <NUM> are meshed between them.

The transmission <NUM> comprises locking means <NUM> of the differential assembly <NUM> to inhibit operation thereof.

According to the above, the locking means <NUM> are configured to connect the chain carrier <NUM> to the casing <NUM>.

In particular, the locking means <NUM> comprise a sleeve <NUM> supported, integral in rotation but free to run along the axis B, for example using a grooved coupling, on the support shaft 18b. The sleeve <NUM> is equipped with a toothing <NUM> that is axial and is configured to assume a first position in which the toothing <NUM> cooperates with another toothing <NUM> carried rigidly by the casing <NUM> and a second position in integral rotation with the support shaft 18b, in neutral.

The sleeve <NUM> is controlled using actuator means <NUM> controlling the selection of the sleeve <NUM> similarly to the selection of the toothed wheels <NUM>, <NUM> and, thus, not further described for brevity's sake. In particular, the elastic means <NUM> keep the sleeve in a rest condition so that the sleeve <NUM> rotates idly with the support shaft 18b.

Referring to <FIG>, the relative arrangement of the couplings <NUM>, <NUM>, the input clutch <NUM>, the electric motor <NUM>, and the support shaft <NUM> is clear, where it should be noted that the electric motor <NUM> and the input clutch <NUM> are carried on the same side as the casing <NUM>. In particular, the electric motor <NUM> is connected to the outside of the casing <NUM> so that its output shaft passes through the casing in the space <NUM>.

In particular, the axis B is placed vertically below the axes A, D of the input clutch <NUM> of the electric motor <NUM>. In particular, the axis C of the support shaft <NUM> coincides with a vertical axis passing through the axis B and is vertically placed between the axes A and D.

In addition, the input clutch <NUM> and the motor <NUM> are placed so that the respective axes A, D are symmetrical to the vertical axis passing through the axes B and C.

Clearly, additional mechanical elements such as additional, sliding, rolling supports, gaskets, and fasteners although illustrated are not described for brevity's sake and since they relate to particular constructions that may vary depending on different assembly and manufacturing settings.

The operation of the traction assembly <NUM> according to the invention as described above is as follows.

In a first, purely thermal, operating condition, the torque released to the couplings <NUM>, <NUM> is exclusively provided by the input clutch <NUM>. In this configuration, represented by the combination of the states in <FIG> and <FIG>, the actuator means <NUM> select one of the toothed wheels <NUM>, <NUM> so that it is integral with the shaft <NUM> and keep the toothed wheels <NUM>, <NUM> idle in relation to the shaft <NUM>. The torque provided thus to the shaft <NUM> flows via the coupling with the corresponding toothed wheel <NUM>, <NUM> to the support shaft <NUM> and, via the gear between the toothings <NUM> and <NUM>, to the differential <NUM>. Here, as is known in itself, it is distributed to the toothed wheels 17a, 17b and, thus, to the hubs 18a, 18b.

In a second operating condition, purely electrical, the torque released to the couplings <NUM>, <NUM> is provided exclusively by the electric motor <NUM>. In this configuration, represented by the combination of the states in <FIG> and <FIG>, the actuator means <NUM> select one of the toothed wheels <NUM>, <NUM> so that it is integral with the shaft <NUM> and keep the toothed wheels <NUM>, <NUM> idle in relation to the shaft <NUM>. The torque provided thus to the shaft <NUM> flows via the coupling with the corresponding toothed wheel <NUM>, <NUM> to the support shaft <NUM> and, via the gear between the toothings <NUM> and <NUM>, to the differential <NUM>. Here, as is known in itself, it is distributed to the toothed wheels 17a, 17b and, thus, to the hubs 18a, 18b.

In a third, hybrid, operating condition, the torque released to the couplings <NUM>, <NUM> is provided both by the electric motor <NUM> and by the input coupling or only by the latter and part is used by the electric motor <NUM> as generator. In this configuration, represented by the combination of the states in <FIG> and <FIG>/5V, the actuator means <NUM> select one of the toothed wheels <NUM>, <NUM> so that it is integral with the shaft <NUM> and the actuator means <NUM> select one of the toothed wheels <NUM>, <NUM> so that it is integral with the shaft <NUM>. The torque provided thus to the shafts <NUM>, <NUM> (or resisting the shaft <NUM>) flows via the corresponding toothed couplings to the support shaft <NUM>, being added according to the relevant sign, and via the gear between the toothings <NUM> and <NUM>, to the differential <NUM>. Here, as is known in itself, it is distributed to the toothed wheels 17a, 17b and, thus, to the hubs 18a, 18b.

In each of the three operating conditions described above, each equipped with two speeds, three operating variants as described below can also be selected.

In a first operating variant (<FIG>), the selector means <NUM> keep the hub 2b of the front coupling <NUM> separated from the hub 18a of the toothed wheel 17a. In this way, the vehicle operates according to a rear traction configuration and all the traction torque flows towards the rear coupling <NUM>.

In a second operating variant (<FIG>), the selector means <NUM> make the hub 2b integral with the front coupling <NUM> separated from the hub 18a of the toothed wheel 17a. In this way, the vehicle operates according to an integral traction configuration and the differential <NUM> distributes the traction torque among the couplings <NUM> and <NUM>.

In a third operating variant (<FIG>), potentially combined with the two preceding ones, the selector means <NUM> make the chain carrier <NUM> integral with the casing <NUM>, locking the differential and making the rear coupling rotate (as illustrated or both combining with the operation in <FIG>) at the same speed as the chain carrier <NUM>.

In view of the operations included above in <FIG> and <FIG>, the vehicle comprises, advantageously, a front axle equipped with free-wheeling devices, advantageously integrated in wheels, configured to enable the operation in neutral of the hub since the front coupling <NUM> is not integral with the hub 18a.

The advantages of a traction assembly according to the invention are clear from the foregoing.

The traction system makes it possible, as shown by the high number of operating combinations illustrated, to provide a great variety of traction transmission ratios that are completely thermal, completely electric, hybrid, those with integral or rear traction, or with locked differential.

The traction system is also particularly compact and uses few mechanical elements; thus, the manufacturing costs are reduced.

Again, although all the rotating mechanical elements are inside the casing of the transmission, which is lubricated, the service life of the traction system is increased and the maintenance costs decrease.

Lastly, it is clear that modifications and variations may be made to the traction assembly and vehicle manufactured according to the present invention, without however departing from the scope of protection defined by the claims.

For example, it is clear that the toothed wheels described, the differential, and other types of mechanical connection may be replaced by equivalent devices.

Similarly, the number of electric motors or the shape of the casing may vary or, again, the reduction stage may involve more speed shifts.

Claim 1:
A traction assembly (<NUM>) for a vehicle, said traction assembly (<NUM>) comprising a first and a second coupling (<NUM>, <NUM>) configured to be connected respectively to a front axle and a rear axle of said vehicle, a input clutch (<NUM>) configured to be connected to an output shaft of an internal combustion engine of said vehicle and at least one electric machine (<NUM>), said traction assembly (<NUM>) comprising a casing (<NUM>) defining a housing (<NUM>) and a transmission (<NUM>) housed in said housing (<NUM>) and configured to allow torque transmission between said input clutch (<NUM>), the at least one electric machine (<NUM>) and the couplings (<NUM>, <NUM>), said transmission (<NUM>) being controlled so as to allow torque transmission according to one of:
- a mode where only said input clutch (<NUM>) provides torque to said couplings (<NUM>, <NUM>);
- a mode where only said at least one electric machine (<NUM>) supplies torque to said couplings (<NUM>, <NUM>); and
- a mode where both said input clutch (<NUM>) and said at least one electric machine (<NUM>) supplies torque to said couplings (<NUM>,<NUM>), wherein said transmission (<NUM>) comprises a differential (<NUM>) comprising a first output hub (18a) connectable to said first coupling (<NUM>) and a second output hub (18b) connectable to said second coupling (<NUM>), said hubs (18a, 18b) and said couplings (<NUM>, <NUM>) being coaxial to each other along an axis (B),
said transmission (<NUM>) comprising a first shaft (<NUM>) supported rotationally free around an axis (A) on said casing (<NUM>), said input clutch (<NUM>) being connectable to said shaft (<NUM>),
said transmission (<NUM>) comprising a second shaft (<NUM>) supported in a rotationally free way around an axis (D) on said casing (<NUM>), said at least one electric machine (<NUM>) being connectable to said shaft (<NUM>),
said first and second shafts (<NUM>, <NUM>) being operatively connected to said differential (<NUM>) through at least one torque transmission ratio.