Improved axle / beam of electric tractor

Abstract

The invention relates to an improved axle / beam of an electric tractor. An electric tractor axle / electric beam for a vehicle, i.e. An electric vehicle axle / electric beam, comprises at least one electric machine (2), a pair of drive axles (4 ', 4' ') each connected to a respective wheel of the vehicle, and a transmission chain operatively connecting the electric machine (2) to the pair of drive axles (4', 4 ''), the transmission chain comprises a first transmission system (5), a second transmission system (7) and a differential unit (8) operatively interposed in series between at least one electric machine and a pair of drive shafts (4 ', 4' '), the drive shafts (4', 4 '') being coaxial to the longitudinal axis (A) of the axle (1), the electric machine (2) being oriented by an axis (B) parallel and spaced apart from the longitudinal axis (A).

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims the priority of Italian patent application no. 102023000021978 filed on October 20, 2023, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] The present invention relates to vehicle axles / beams.

[0004] A preferred, but not exclusive, application of the invention is an electric traction vehicle axle / beam, a so-called "e-axle" or "e-beam". Reference will be made to this application by way of example below. Background Art

[0005] As is known, there is an increasing need to reduce polluting emissions caused by internal combustion engines used to operate vehicles, in particular for achieving traction of the vehicles.

[0006] This need is even greater for light commercial vehicles (LCV), medium commercial vehicles (MCV) or heavy commercial vehicles (HCV) such as trucks and motor vehicles in general.

[0007] For this purpose, there are known solutions: electric axles or electric beams, i.e. electric traction axles or electric beams, wherein the axle / beam supports one or more electric machines configured to exchange torque with the drive shaft of the axle and therefore with the wheels, in order to provide or generate power depending on the use of the vehicle.

[0008] More specifically, it should be noted that the axle is the only component connecting the two hubs that performs a support function, while the beam is the component connecting the two hubs but where the drive shaft and differential assembly are also present as well as the input point for tractive torque.

[0009] Examples of these electric axles are shown in patents US2022 / 0250457A1, US2020 / 0282827A1 and US2022 / 0065334A1.

[0010] These solutions involve using the electric machine in a so-called “coaxial” configuration, in other words, in which the axis of the electric machine is coaxial with the axis of the axle / beam drive shaft.

[0011] Although this configuration is advantageous with regard to the direct assembly of the element on the axle itself, it is particularly disadvantageous with regard to the dimensions in the axial direction.

[0012] In fact, the positioning of the particularly bulky electric motor limits the positioning of other functional elements unless the longitudinal dimension of the axle is increased.

[0013] Since this extension is not always possible due to the size of the components already present on the axle (suspension, brake system components, frame components, axle track limiters, etc.), the transmission connecting the motor to the wheel or the motor itself must be resized, effectively reducing the power and performance available to the axle or beam.

[0014] As a result, the versatility of providing torque and power over extended intervals, which is an essential feature for providing an electric axle or electric beam that can be used under different vehicle operating conditions, is compromised.

[0015] Therefore, there is a need to provide an electric axle or electric beam which can have a reduced size while maintaining as extended an operating range as possible in terms of torque and power to meet various vehicle operating conditions.

[0016] The object of the present invention is to meet the needs outlined above in an optimal and inexpensive manner. Summary of the invention

[0017] The above objects are achieved by the electric traction vehicle axle / beam as claimed in the various aspects of the invention which are an integral part of the present description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] For a better understanding of the present invention, preferred embodiments are described below by way of non-limiting examples and with reference to the accompanying drawings, in which:

[0019] · Figure 1 is a diagram indicating the operational relationships between the various functional systems of an electric traction vehicle axle / beam according to a first embodiment which is not a part of the present invention but is useful in its operation;

[0020] · Figure 2 is a schematic diagram of an electric traction vehicle axle / beam according to the first embodiment mentioned above;

[0021] · Figure 3 is a diagram indicating the operational relationship between various functional systems of an electric traction vehicle axle / beam according to a second embodiment of the present invention;

[0022] ● Figure 4 is a schematic diagram of an electric traction vehicle axle / beam according to a second embodiment of the present invention;

[0023] · Figure 5 is a diagram indicating the operational relationship between various functional systems of an electric traction vehicle axle / beam according to a third embodiment of the present invention;

[0024] · Figure 6is a schematic diagram of an electric traction vehicle axle / beam according to a third embodiment of the present invention;

[0025] · Figure 7 is a diagram indicating the operational relationship between various functional systems of an electric traction vehicle axle / beam according to a fourth embodiment of the present invention;

[0026] · Figure 8 is a schematic diagram of an electric traction vehicle axle / beam according to a fourth embodiment of the present invention;

[0027] · Fig. 9 is a diagram indicating the operational relationship between various functional systems of an electric traction vehicle axle / beam according to a fifth embodiment of the present invention;

[0028] · Fig.10 is a schematic diagram of an electric traction vehicle axle / beam according to a fifth embodiment of the present invention;

[0029] ● Fig.11 is a diagram indicating the operational relationship between various functional systems of an electric traction vehicle axle / beam according to a fifth embodiment of the present invention;

[0030] · Fig.12 is a schematic diagram of an electric traction vehicle axle / beam according to a fifth embodiment of the present invention;

[0031] · Fig.13 is a diagram indicating the operational relationship between various functional systems of an electric traction vehicle axle / beam according to a sixth embodiment of the present invention; and

[0032] · Fig.14 is a schematic diagram of an electric traction vehicle axle / beam according to a sixth embodiment of the present invention. DETAILED DESCRIPTION

[0033] For simplicity, the expressions axle / beam or electric axle / electric beam will be used below to avoid repetition, since the invention can be applied to both architectures.

[0034] The attached diagram ( Figure 1 , Figure 3 , Figure 5 , Figure 7 , Fig. 9 , Fig.11 , Fig.13 ) schematically depicts a drive train for exchanging torque in an electric axle / beam 1 or electric axle / electric beam between an electric motor 2 and a pair of wheels 3 supported by a drive shaft 4', 4" of the electric axle 1.

[0035] As is known, the motor 2 is electrically connected to a power source, such as a battery pack of the vehicle (not shown), and is configured to exchange power with the power source, in particular to receive power to generate torque for the wheels 3 or to receive torque from the wheels 3 to introduce power into the motor.

[0036] As schematically depicted, the drive train of the electric axle 1 comprises in sequence a first transmission system 5 , a second transmission system 7 and a differential unit 8 between the motor 2 and the wheels 3 .

[0037] Advantageously ( Figure 3 , Figure 5 , Figure 7 , Fig. 9 , Fig.11 , Fig.13 ), there may be a speed ratio changing system 6 between the first transmission system 5 and the second transmission system 7. The term "transmission system" refers to a system for changing the torque / speed between input and output, and the ratio of the transmission system to the output or input may be greater than 1, less than 1 or equal to 1. Advantageously, the second transmission system 7 is designed as a speed reducer.

[0038] A differential unit 8 is interposed between the drive shafts 4 ′, 4 ″. Optionally, the drive shafts 4 ′, 4 ″ may each be connected to a wheel by means of a wheel hub reduction system 9 .

[0039] Optionally, there may be a differential locking system 11 arranged between the differential unit 8 and one of the drive shafts 4', 4", and as an additional option, there may be a parking brake system 12, which is configured to operatively cooperate with the second transmission system 7 or the differential unit 8 to lock the movement of the electric axle 1.

[0040] Likewise, optionally, there may be an oil distribution system 13 operatively interposed between the differential unit 8 and one of the drive shafts 4 ′, 4 ″ and the corresponding wheel hub reduction system 9 .

[0041] Between the wheels 6 and the differential unit 8, there may also optionally be a disconnection system 14, which connects or disconnects one of the two drive shafts by actually disconnecting at least one motor 2 from the drive chain upstream of the differential unit 8, thereby making vehicle traction possible.

[0042] Reference Figure 2 It should be noted that the operating shaft 2' of the motor 2, i.e. the axis of the shaft supported by the rotor of the motor 2, is coaxial with the axis B, which is parallel to the longitudinal axis A of the axle / beam 1, i.e. the longitudinal axis A coaxial with the drive shaft 4', 4", and is spaced apart from the longitudinal axis A.

[0043] For the sake of simplicity, this configuration in which the axes A, B are separated and parallel will be defined as an "off-axis configuration" below.

[0044] Although not included Figure 2 In the embodiment of the present invention, the axle 1 comprises a housing designed to accommodate the described transmission chain, a part of the drive shaft 4', 4", and to support the motor 2, in particular the stator of the motor 2. The housing defines a space designed to accommodate the following elements of the transmission chain, thereby isolating these elements from the external environment.

[0045] An operating shaft 2 ′ of the electric machine 2 is operatively connected to the input shaft 15 by means of a first transmission system 5 .

[0046] Advantageously, the input shaft 15 is supported so as to rotate freely relative to one of the two drive shafts 4', 4"; for simplicity, in this description reference will be made to the left drive shaft 4', but it is clear that what is described can be exchanged in a mirror-like manner between the left and right drive shafts.

[0047] Advantageously, the first transmission system 5 defines at least one transmission ratio between the input shaft 15 and the operating shaft 2' and is preferably manufactured as a parallel shaft reduction system. Specifically, in an embodiment, the transmission ratio is defined by two speed jumps 5', 5", which are defined by corresponding gear mechanisms.

[0048] In particular, the transmission system includes: a first gear mechanism 5', which is defined by a first gear 5a rigidly supported by the operating shaft 2' and a second gear 5b rigidly supported by the supporting shaft 16; and a second gear mechanism 5", which includes a third gear 5c rigidly supported by the supporting shaft 16 and a fourth gear 5d rigidly supported by the input shaft 15.

[0049] Clearly, although not illustrated, additional gear configurations may be applied, such as, for example, a configuration in which the second gear 5c is not included and the first gear 5a directly meshes with the second gear 5b, as implemented in some embodiments described below.

[0050] The second transmission system 7 is advantageously made as an epicyclic assembly and therefore comprises a sun gear 7 ′, a plurality of planetary gears 7 ″ and a crown 7 ′″.

[0051] The sun gear 7' is advantageously supported by the left drive shaft 4' and, as is known, meshes with a plurality of planetary gears 7", which in turn mesh with a crown 7'", which is rigidly supported by a portion of the axle / beam 1, such as a housing (not shown). The planetary gears 7 are supported by pins connected to a carrier 7a.

[0052] exist Figure 2In the embodiment in FIG. 1 , the sun gear 7 ′ is supported by the input shaft 15 .

[0053] The differential unit 8 is of the type with bevel gears and, as known, comprises a plurality of planetary gears 8' driven by the carrier 7a and meshing with a pair of bevel wheels 8a, 8b rigidly supported by the left 4' and right 4" drive shafts.

[0054] In particular, it should be noted that the left drive shaft 4' comprises a first portion defining the lubricating system 13 and a second portion operatively connected to the gear 8a. Thus, in this case, the bevel gear 8a is supported by the portion defining the lubricating system 13.

[0055] As is known, the differential locking system 11 is configured to lock the action of the differential unit 8, thereby securely connecting the two drive shafts 4', 4" by connecting one of the two drive shafts 4', 4" with the differential unit container.

[0056] In the illustrated embodiment, the differential locking system 11 essentially comprises a sleeve 11 b supported so as to slide along the axis A from the hub 11 a and therefore from the right drive shaft 4 ″ by means of a connection, such as a grooved connection, which can be moved due to the action of actuator means not illustrated.

[0057] The sleeve 11 b also defines a toothing 11 c configured to selectively cooperate, according to its movement along the axis A, with a toothing formed on a portion 17 integrally supported by the carrier 7 a .

[0058] The wheel hub reduction system 9 , if included, can be manufactured in different ways as desired and, therefore, for the sake of brevity, will not be described further.

[0059] Similarly, the parking lock system 12 may be manufactured in different forms and on different operative parts of the axle / beam 1 and therefore will not be described further for the sake of brevity.

[0060] The operation of the embodiment of the electric traction vehicle axle / beam according to the embodiment described above is as follows.

[0061] In a first operating condition in which the electric machine 2 is used as an electric motor, the electric machine 2 provides torque to the first transmission system 5, which transmits the torque to the input shaft 15 by increasing the value of the torque and thus reducing the rotational speed. The torque from the input shaft 15 is transmitted from the sun gear 7' through the planetary gears 7" to the carrier, and from the carrier to the differential unit 8. From the differential unit 8, as is known, the torque is distributed between the drive shafts 4', 4", and therefore to the wheels 3 by means of the hub reduction system 9 - if included - or directly to the wheels 3.

[0062] The differential unit can be locked by means of a differential locking system 11 .

[0063] In a second operating configuration in which the motor 2 acts as a generator, torque is provided by wheels 3 driven by the movement of the vehicle and in the opposite direction following the same drive train previously described to the motor 2 which thus generates electricity from the torque received as input.

[0064] exist Figure 3 and Figure 4 In the second embodiment, compared with the first embodiment, a speed selector gearbox 6 is present between the first transmission system 5 and the second transmission system 7 .

[0065] In this embodiment, if Figure 4 As illustrated in FIG. 1 , due to the speed ratio changing system 6 , the input shaft 15 may be connected to the carrier 7 a or the sun gear 7 ′.

[0066] In the depicted embodiment, the speed selector gearbox 6 basically comprises a sleeve 6a defining a first toothing 6' and a second toothing 6".

[0067] Advantageously, the second toothing 6 ″ is configured to cooperate in sliding motion with the input shaft 15 along the axis A, defining a groove-type coupling with the input shaft 15 . This movement is regulated using actuator means, not shown or described for the sake of simplicity.

[0068] According to the movement along the axis A initially described, the first tooth portion 6' can respectively cooperate with the tooth portion 7b rigidly supported by the carrier 7a (reduction ratio equal to 1) or with the tooth portion 7c rigidly supported by the sun gear 7' (maximum reduction ratio), or alternatively with neither (idle motion configuration).

[0069] The operation of the embodiment of the electric traction vehicle axle / beam according to the embodiment of the invention described above is as follows.

[0070] In a first operating condition, in which the electric machine 2 is used as an electric motor, the electric machine 2 provides a torque to the first transmission system 5, which transmits the torque to the input shaft 15 by increasing the value of the torque and thus reducing the rotational speed. Depending on the position of the sleeve 6a, the torque is transmitted directly to the carrier 7a and thus to the differential unit 8, or the value is otherwise changed by means of a transmission between the sun gear 7' and the planetary gears 7". The torque from the input shaft is transmitted from the sun gear 7' via the planetary gears 7", to the carrier, and from the carrier to the differential unit 8. From the differential unit 8, as is known, the torque is distributed between the drive shafts 4', 4", and thus transmitted to the wheel 3 by means of the hub reduction system 9 - if included - or directly to the wheel 3.

[0071] The differential unit can be locked by means of a differential locking system 11 .

[0072] In a second operating configuration in which the motor 2 acts as a generator, torque is provided by wheels 3 driven by the movement of the vehicle and in the opposite direction following the same drive train previously described to the motor 2 which thus generates electricity from the torque received as input.

[0073] exist Figure 5 and Figure 6 In the third embodiment schematically depicted in FIG. 1 , relative to the second embodiment, the second reduction system 7 comprises a pair of epicyclic gearings operating in series.

[0074] In particular, the second epicyclic gearing comprises a second sun gear 70 ′, a plurality of second planet gears 70 ″, a second crown 70 ″′ connected to the housing of the beam / axle.

[0075] The second sun gear 70 ′ is advantageously connected torque-rigidly to the carrier 7 a of the first epicyclic gearing and meshes with a plurality of second planet gears 70 ″ which in turn mesh with a second crown 70 ′″ rigidly supported by the same rigid part of the axle 1 .

[0076] The plurality of second planetary gears 70" are connected to a carrier 70a which is operatively connected to the differential unit 8 and differential locking system 11 - if included, similar to that described for the first embodiment and therefore not repeated for the sake of brevity.

[0077] The operation of the embodiment of the electric traction axle according to the embodiment of the invention described above is as follows.

[0078] In a first operating condition, in which the electric machine 2 is used as an electric motor, the electric machine 2 provides a torque to the first transmission system 5, which transmits the torque to the input shaft 15 by increasing the value of the torque and thereby reducing the rotational speed. Depending on the position of the sleeve 6a, the torque is transmitted directly to the carrier 7a and thereby to the second sun gear 70' and to the planetary gears 70", towards the differential unit 8, or additionally, the value is changed by means of a transmission between the first sun gear 7' and the first planetary gears 7". From the differential unit 8, as is known, the torque is distributed between the drive shafts 4', 4", and thereby transmitted to the wheels 3 by means of a hub reduction system 9 (if included). The differential unit can be locked by means of a differential locking system 11.

[0079] In a second operating configuration in which the motor 2 acts as a generator, torque is provided by wheels 3 driven by the movement of the vehicle and in the opposite direction following the same drive train previously described to the motor 2 which thus generates electricity from the torque received as input.

[0080] exist Figure 7 and Figure 8 In the fourth embodiment shown, there is a compound epicyclic gearing device that is made in a different manner than the third embodiment described above.

[0081] Certain epicyclic systems in which the planetary gear has two toothed belts connected together rigidly with respect to torque are called "compound type".

[0082] In particular, the compound epicyclic gearing in this embodiment comprises a first sun gear 7' supported in free rotation on a second sun gear 7a'. These sun gears can be connected by means of a speed selector gearbox 6 which makes it possible to connect the input shaft 15 to a first part 7c integral with the first sun gear 7' or to a second part 7c' integral with the second sun gear 70', or to the carrier 7a by means of a part 7b connected to the carrier 7a.

[0083] The first sun gear 7' meshes with a plurality of first planet gears 7", and the second sun gear 7a' meshes with a plurality of second planet gears 70". In this embodiment, the plurality of first planet gears 7' are rigidly connected to a plurality of second planet gears 70", and the plurality of second planet gears 70" mesh with a crown 70"' rigidly supported relative to the beam / axle 1.

[0084] The plurality of planetary gears 7', 70' are all supported by the same carrier 7a connected to the differential unit 8 as in the previous embodiment.

[0085] Specifically, in this embodiment, the speed selector gearbox 6 may be configured to assume a third position in which the speed selector gearbox 6 may connect the input shaft 15 to the toothed portion 7b integral with the carrier 7a.

[0086] The operation of the embodiment of the electric traction axle according to the embodiment of the invention described above is as follows.

[0087] In a first operating condition in which the electric machine 2 is used as an electric motor, the electric machine 2 provides a torque to the first transmission system 5, which transmits the torque to the input shaft 15 by increasing the value of the torque and thereby reducing the rotational speed. Depending on the position of the sleeve 6a, the torque is transmitted directly to the carrier 7a or the first sun gear 7' or the second sun gear 7a', so as to drag a differential unit with three distinct transmission ratios according to the drive chain. From the differential unit 8, as is known, the torque is distributed between the drive shafts 4', 4", and therefore to the wheels 3 by means of a hub reduction system 9 (if included). The differential unit can be locked by means of a differential locking system 11.

[0088] In a second operating configuration in which the motor 2 acts as a generator, torque is provided by wheels 3 driven by the movement of the vehicle and in the opposite direction following the same drive train previously described to the motor 2 which thus generates electricity from the torque received as input.

[0089] exist Fig. 9 and Fig.10 In the fifth embodiment schematically depicted in FIG. 1 , relative to the fourth embodiment of the axle / beam 1 , the speed ratio varying system 6 is manufactured differently relative to the previously illustrated embodiments and is configured to provide additional configurations as described below.

[0090] Specifically, in addition to the first sleeve 6a previously described and configured to distribute torque to one of the first sun gear 7' or the carrier 7a (or not to either when idling), the speed ratio change system 6 also includes a second sleeve 6b, which is supported so that it moves from the input shaft 15 along the axis A and selectively cooperates with the additional input shaft 15' by means of a tooth portion 6c.

[0091] The additional input shaft 15' is freely rotatably supported between the drive shaft 4' and the input shaft 15 and integrally supports a second sun gear 7a' which is configured to mesh with a plurality of planetary gears 7a", which are supported by the same carrier 7a and rigidly connected to a plurality of first planetary gears 7", which are individually meshed with the first crown 7'".

[0092] In particular, in the described embodiment, the first sleeve 6a and the second sleeve 6b are arranged on opposite sides of the gear supported by the input shaft 15; in any case, it is clear that the first sleeve 6a and the second sleeve 6b can advantageously be arranged on the same side relative to the gear so as to further reduce the size of the axle 1.

[0093] The operation of the embodiment of the electric traction vehicle axle / beam according to the embodiment of the invention described above is as follows.

[0094] In a first operating condition in which the electric machine 2 is used as an electric motor, the electric machine 2 provides a torque to the first transmission system 5, which transmits the torque to the input shaft 15 by increasing the value of the torque and thus reducing the rotational speed. Depending on the position of the sleeve 6a or 6b, which selectively engages one of the two sun gears 7' or 7a' or the carrier 7a, the torque is transmitted directly to the carrier 7a and thus to the differential unit 8 to the third sun gear 70' and the planetary gears 70", or additionally, the value is changed by means of a transmission between the first sun gear 7' and the first planetary gears 7", or again through the second sun gear 7a' and the second planetary gears 7a". From the differential unit 8, as is known, the torque is distributed between the drive shafts 4', 4", and thus to the wheels 3 by means of the hub reduction system 9 (if included). The differential unit can be locked by means of a differential locking system 11.

[0095] In a second operating configuration in which the electric machine 2 acts as a generator, torque is provided by the wheels 3 driven by the movement of the vehicle and in the opposite direction following the same drive train previously described to the electric machine 2 which thus generates electricity.

[0096] exist Fig.11 and Fig.12 In the sixth embodiment schematically depicted in FIG. 1 , relative to the second embodiment of the axle / beam 1 , the speed ratio varying system 6 is manufactured differently relative to the previously illustrated embodiments and is configured to provide additional configurations as described below.

[0097] Specifically, in addition to the first sleeve 6a previously described and configured to distribute torque to one of the first sun gear 7' or the first carrier 7a (or not to either when idling), the speed ratio change system 6 also includes a second sleeve 6d, which is supported so that it moves along the axis A between the first carrier 7a and the second carrier 70a of two epicyclic reducer assemblies arranged sequentially.

[0098] Additionally, with respect to the described embodiment, the second sun gear 70' is rigidly fixed to a fixed portion of the housing of the axle 1, meshing with a second planetary gear 70" and a crown 70"' (the crown 70"' can rotate), the crown 70"' comprising a first portion 70a"' meshing with the planetary gear and a second portion 70b"' connected to the crown 70"', the second portion 70b"' selectively meshing with the second sleeve 6d, as described below.

[0099] The second sleeve 6d is configured to move along the axis A and defines a first toothing 6f and a second toothing 6e. The first toothing 6f forms a grooved coupling with the first carrier 7a, while the second toothing 6e can mesh directly with the second carrier 70a or with the second portion 70b''' of the second crown 70'''.

[0100] In a first operating condition in which the electric machine 2 is used as an electric motor, the electric machine 2 provides torque to the first transmission system 5, which transmits the torque to the input shaft 15 by increasing the value of the torque and thus reducing the rotational speed. Depending on the position of the sleeve 6a or 6d, the torque is directed differently between the elements of the coaxial epicyclic reducer assembly, thereby producing up to 4 different types of reduction ratios. From the differential unit 8, as is known, the torque is distributed between the drive shafts 4', 4", and therefore to the wheels 3 by means of the hub reduction system 9 (if included). The differential unit can be locked by means of the differential locking system 11.

[0101] In a second operating configuration in which the electric machine 2 acts as a generator, torque is provided by the wheels 3 driven by the movement of the vehicle and in the opposite direction following the same drive train previously described to the electric machine 2 which thus generates electricity.

[0102] exist Fig.13 and Fig.14 In the sixth embodiment schematically depicted in FIG. , a Fig.10 and Figure 4 A combination of the implementation methods in .

[0103] Specifically, the speed ratio changing system 6 includes a transmission element interposed between the input shaft 15 and the additional input shaft 15′. Fig.10 For the sake of brevity, additional details are not included because the structures are similar.

[0104] about Fig.10 , the carrier 7a is directly connected to the differential unit 8 without interposing a second additional reduction stage, e.g. Figure 4 As presented in .

[0105] Additionally, the first transmission system 5 Figure 2 , Figure 4 , Figure 6 and Figure 8 The configuration presented has parallel axes, but is similar in operation.

[0106] The operation of the embodiment of the electric traction vehicle axle / beam according to the embodiment of the invention described above is as follows.

[0107] In a first operating condition in which the electric machine 2 is used as an electric motor, the electric machine 2 provides a torque to the first transmission system 5, which transmits the torque to the input shaft 15 by increasing the value of the torque and thus reducing the rotational speed. Depending on the position of the sleeve 6a or 6b (the sleeve 6a or 6b selectively engages one of the two sun gears 7' or 7a' or the carrier 7a), the torque is transmitted directly to the carrier 7a, to the differential unit 8, or additionally, the value is changed by means of a transmission between the first sun gear 7' and the first planetary gear 7", or again through the second sun gear 7a' and the second planetary gear 7a". From the differential unit 8, as is known, the torque is distributed between the drive shafts 4', 4", and therefore to the wheels 3 by means of the hub reduction system 9 (if included). The differential unit can be locked by means of a differential locking system 11.

[0108] In a second operating configuration in which the electric machine 2 acts as a generator, torque is provided by the wheels 3 driven by the movement of the vehicle and in the opposite direction following the same drive train previously described to the electric machine 2 which thus generates electricity.

[0109] From the above, the advantages of the electric traction axle according to the present invention are clear.

[0110] Thanks to the proposed axle 1 , it is possible to provide an electric axle / electric beam having a reduced longitudinal dimension, while also maintaining a high level of torque / power that can be transmitted by the electrified transmission.

[0111] In particular, due to the proposed reduction system, a high transmission ratio can be provided between the electric machine and the wheel hub in a longitudinally and radially compact manner with respect to the axis of the drive shaft.

[0112] Likewise, the off-axis configuration allows the motor to be comfortably housed outside the space containing the transmission elements, thereby facilitating their assembly and lubrication.

[0113] Finally, it is obvious that modifications and variations may be made to the electric traction axle according to the invention without departing from the scope of protection defined by the claims.

[0114] Clearly, the described epicyclic mechanism as well as the differential unit may be assembled or arranged differently than what has been described, such as with other gears and selectors.

[0115] Alternatively, the shift system can be made with a dog clutch, a radial clutch (with grooves), a clutch element or a synchronizer element as described above. In particular, a "power shift" clutch can be used.

[0116] Similarly, the actuator and hub transmission system can be manufactured in different ways.

[0117] In particular, the actuator element can be manufactured in various ways, i.e., for example by means of: a piston, a drum, an electric actuator linkage using air or oil, an electromagnetic actuator linkage, a coaxial actuator linkage, or a remote actuator linkage with stable or monostable control, a rotary actuator linkage or a linear actuator linkage, etc.

[0118] Additionally, if a hub reduction system is included, it may be of the coaxial type between the drive shaft and wheel axis, or offset arrangement (spaced from parallel axis) creating a "portal" architecture designed to increase the free distance between the axis of the differential unit (and therefore the transmission) and the ground.

[0119] Likewise, it is clear that the illustrated embodiments can be combined as long as they are mechanically compatible.

Claims

1. An electric traction axle / beam for a vehicle, i.e. an electric axle / electric beam (1), comprising at least one electric motor (2), a pair of drive shafts (4', 4") and a transmission chain operatively connecting the at least one electric motor (2) to the pair of drive shafts (4', 4"), The transmission chain comprises a first transmission system (5), a second transmission system (7) and a differential unit (8) operatively interposed in series between the at least one motor (2) and the pair of drive shafts (4', 4"). The drive shaft (4', 4") is coaxial with the longitudinal axis (A) of the axle (1), and the motor (2) is supported on an axis (B) which is parallel to and different from the longitudinal axis (A). in, The second transmission system (7) is of the epicyclic type, comprising a sun gear (7'), a crown (7'") connected to a portion of the axle (1), and a plurality of planetary gears (7") meshing between the sun gear (7') and the crown (7'") and connected by a carrier (7a), the carrier (7a) being operatively connected to the differential unit (8), The electric axle / electric beam (1) further comprises at least one speed ratio changing system (6) operatively interposed between the first transmission system (5) and the second transmission system (7), The speed ratio changing system (6) is configured to connect the input shaft (15) to one of the sun gear (7') or the carrier (7a), or to disconnect the input shaft (15) from the second transmission system (7).

2. The electric axle / electric beam according to claim 1, wherein: The motor (2) drives an operating shaft (2'), which is operatively connected to an input shaft (15) via the first transmission system (5), the input shaft (15) being carried in a freely rotating manner by one of the drive shafts (4', 4") and operatively connected to the second transmission system (7) via the speed ratio changing system (6), the first transmission system (5) being a parallel shaft transmission system defining at least one speed jump (5', 5") between the operating shaft (2') and the input shaft (15).

3. The electric axle / electric beam according to claim 1, wherein: The speed ratio changing system (6) comprises a first sleeve (6a), which is movably carried by the input shaft (15) along the axis (A) and is provided with a tooth portion (6'), wherein the tooth portion (6') is configured to be selectively operatively connected to corresponding tooth portions (7b, 7c), and the corresponding tooth portions (7b, 7c) are respectively integral with the carrier (7a) and the sun gear (7').

4. The electric axle / electric beam according to claim 1, wherein: The sun gear (7') is coaxial with the axis (A).

5. The electric axle / electric beam according to claim 3, wherein: The first sleeve (6a) is coaxial with the axis (A).

6. The electric axle / electric beam according to claim 1, wherein: The second transmission system (7) includes a second sun gear (70') rigidly supported by the carrier (7a), a second crown (70'") connected to a portion of the axle (1), and a plurality of second planetary gears (70") meshing between the second sun gear (70') and the second ring (70'"), the plurality of planetary gears (70") being connected to the second carrier (70a), and the second carrier (70a) being operatively connected to the differential unit (8).

7. The electric axle / electric beam according to claim 1, wherein: The transmission system (7) includes a second sun gear (7a'), a plurality of second planetary gears (7a") meshing between the second sun gear (7a') and the crown (70'"), the plurality of second planetary gears (7a") being rigidly connected to the plurality of planetary gears (7') and carried by the same carrier (7a), the speed ratio change system (6) including a first sleeve (6a), the first sleeve (6a) being movably carried by the input shaft (15) along the axis (A) and being provided with a tooth portion (6'), the tooth portion (6') being configured to be selectively operatively connected to corresponding tooth portions (7b, 7c, 7c'), the corresponding tooth portions (7b, 7c, 7c') being respectively integral with the carrier (7a), the sun gear (7') or the second sun gear (7a').

8. The electric axle / electric beam according to claim 1, wherein: The transmission system (7) comprises a second sun gear (70') rigidly carried by the carrier (7a), a second crown (70'") and a plurality of second planetary gears (70") meshing between the second sun gear (70') and the second crown (70'"), the plurality of planetary gears (70'") being connected to the second carrier (70a), the second carrier (70a) being operatively connected to the differential unit (8), And wherein the transmission system (7) comprises a third sun gear (7a'), a plurality of second planetary gears (7a") meshing with the third sun gear (7a'), the plurality of second planetary gears (7a") being rigidly connected to the planetary gears (7") and carried by the same carrier (7a), the carrier (7a) being rigidly connected to the second sun gear (70'), The speed ratio changing system (6) includes a first sleeve (6a) and a second sleeve (6b), wherein the first sleeve (6a) is movably carried by the input shaft (15) along the axis (A) and is provided with a tooth portion (6') configured to be selectively operatively connected to a corresponding tooth portion (7b, 7c) integral with the carrier (7a) or the sun gear (7'), and the second sleeve (6b) is movably carried by the input shaft (15) along the axis (A) and is provided with a tooth portion (6c) configured to be selectively operatively connected to a tooth portion integral with the third sun gear (7a').

9. The electric axle / electric beam according to claim 1, wherein: The system (7) comprises a second sun gear (70') fixed in rotation by the axle (1), a second crown (70'") and a plurality of second planetary gears (70") meshing between the second sun gear (70') and the second crown (70'"), the plurality of planetary gears (70") being connected to a second carrier (70a) operatively connected to the differential unit (8), The speed ratio changing system (6) includes a first sleeve (6a) and a third sleeve (6d), wherein the first sleeve (6a) is movably carried by the input shaft (15) along the axis (A) and is provided with a tooth portion (6') configured to be selectively operatively connected to a corresponding tooth portion (7b, 7c) integral with the carrier (7a) or the sun gear (7'), and the third sleeve (6d) is movably carried by the support (7a) along the axis (A) and is provided with a tooth portion (6f) configured to be selectively operatively connected to a tooth portion integral with the second gear carrier (70a) or the second crown portion (70"').

10. The electric axle / electric beam according to claim 1, wherein: The transmission system (7) comprises a second sun gear (7a'), a plurality of second planetary gears (7a") meshing between the second sun gear (7a') and the crown (70'"), the plurality of second planetary gears (7a') being rigidly connected to the plurality of planetary gears (7') and carried by the same carrier (7a), the speed ratio changing system (6) comprising a first sleeve (6a), the first sleeve (6a) being movably carried by the input shaft (15) along the axis (A) and being provided with a toothed portion (6') configured to be selectively operatively connected to corresponding teeth (7b, 7c) respectively integral with the carrier (7a) and the second sun gear (7'), The speed ratio changing system (6) includes a second sleeve (6b), which is movably carried by the input shaft (15) along the axis (A) and is provided with a tooth portion (6c) configured to be selectively operatively connected to a tooth portion integral with the second sun gear (7a').

11. The electric axle / electric beam according to claim 9, wherein: The first sleeve (6a) and the second sleeve (6b) are arranged on the same side of a gear wheel rigidly carried by the input shaft (15).

12. The electric axle / electric beam according to claim 1, wherein: The differential unit (8) comprises a plurality of planetary gears (8') which are driven by the second transmission system (7) and mesh with a first bevel gear (8a) and a second bevel gear (8b) carried by respective drive shafts (4', 4").

13. The electric axle / electric beam according to claim 1, comprising a differential locking system (11) configured to inhibit the torque distribution function of the differential unit (8).

14. The electric axle / electric beam according to claim 1, further comprising an optional wheel hub reduction system (9) operatively interposed between each wheel (3) and the corresponding drive shaft (4', 4").

15. The electric axle / electric beam according to claim 1 further includes a parking brake system (12), which is configured to operatively cooperate with at least one of the second transmission system (7) and / or the differential unit (8) to block the movement of the electric axle / electric beam (1).

16. The electric axle / electric beam according to claim 1 comprises a housing, which is suitable for supporting the motor (2), the drive shaft (4', 4') and defining a space separated from the external environment, the space being used to accommodate the first transmission system (5), the at least one speed ratio changing system (6), the second transmission system (7) and the differential unit (8).

17. The electric axle / electric beam according to claim 1, comprising a disconnect system of the drive shaft (4', 4") to allow a disconnect function of the drive shaft (4', 4") from the transmission chain.

18. A vehicle comprising the electric axle / electric beam according to claim 1.

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