Modular electric traction system

Abstract

A bridge assembly (40) for a heavy vehicle comprising a transverse element (41) rigidly connecting at least one pair of wheels (102, 103), and an electric traction module (1), movably supported by the transverse element (41) and comprising at least one electric motor (2), a first and a second output shaft (16, 17), and a transmission (3) configured to connect at least one electric motor (2) with at least one of the first and second output shafts (16, 17), the electric traction module (1) further comprising a casing (8) configured to define a volume (9) in which the electric motor (2) and the transmission (3) and at least a portion of the first and second output shafts (16, 17) are housed. Figure for the abbreviation: Fig. 5

Description

Title of the invention: Modular electric traction system Technical field

[0001] The present invention relates to a traction system for commercial vehicles, in particular an electric and modular traction system for commercial vehicles. State of the art

[0002] It is known to use, on commercial vehicles, internal combustion engine traction systems usually connected to a rear rigid axle, that is to say a transverse load-bearing element, the axle, which rigidly connects the two wheels and which contains the two half-axles for traction of the wheels connected to each other by a differential. Such a rigid axle is connected to the chassis of the vehicle by means of suspensions, as schematically illustrated in [Fig.l].

[0003] In the [Fig.l] mentioned above, the rigid axle 1' of a vehicle 10' essentially comprises an axle 2' connecting at its respective ends, the right and left wheels 3', 4' and carrying the differential 5' in a known manner, at the center of the axle 2'. The axle 2' is connected to a chassis 6' of the vehicle 10' by means of respective suspensions 7', 8' of any typology.

[0004] A rigid bridge structure 1' of the type illustrated in [Fig.l] allows the transport of heavy loads in a reliable manner and to maintain, in a controlled manner, the geometry of movement of the wheels, reducing wear.

[0005] However, the rigid bridge 1' must be reconfigured each time the spans on the bridge and the powers involved change and therefore the structure of the bridge 2' and the differential 5' must be reconfigured. Such a requirement is all the more felt in the field of electric / hybrid traction in which it is necessary to provide a location for the electric traction motor, the dimensions of which change as the torque supplied changes.

[0006] There is therefore a need to provide a traction system that is as versatile as possible and usable on different vehicles with different types of axle, suspension and transported weight.

[0007] That is to say, there is a need for a system that can satisfy the component range of the transmission components regardless of their power.

[0008] The aim of the present invention is to satisfy the requirements set out above. Summary of the invention

[0009] The above-mentioned object is achieved by a bridge assembly comprising a modular electric traction system.

[0010] The invention relates to a bridge assembly for a heavy vehicle, said bridge assembly comprising a transverse element rigidly connecting together at least one pair of wheels, said bridge assembly element comprising an electric traction module, movably carried by said transverse element, said traction module comprising at least one electric motor, a first and a second output shaft and a transmission configured to connect said at least one electric motor with at least one of said first and second output shafts, said electric traction module further comprising a casing configured to define a volume in which said electric motor and said transmission and at least a portion of said first and second output shafts are housed.

[0011] The invention may be supplemented by the following characteristics, taken alone or in any of their technically possible combinations:

[0012] - a first and a second half-axle, said first half-axle being connected said first output shaft via a first constant velocity joint and said second half-axle being connected to said second output shaft via a second constant velocity joint,

[0013] - said module comprises a single electric motor and in which said transmission comprises a differential connected to said first and second output shafts,

[0014] - said module comprises a first electric motor and a second motor electric, said transmission comprises a first gear system connecting said first electric motor and said first output shaft and a second gear system connecting said second electric motor to said second output shaft,

[0015] - said transmission comprises epicyclic gears,

[0016] - said at least one electric motor has a basic power P of between 80 and 150 kW,

[0017] - said at least one electric motor and said transmission are sized for provide a module with a power equal to N times the basic power P, where N is a predetermined integer between 2 and 5.

[0018] The invention also relates to a vehicle comprising such a rigid axle assembly. Brief description of the drawings

[0019] For a better understanding of the present invention, a preferred embodiment is described in the following part, by way of non-limiting example and with reference to the attached drawings, in which:

[0020] [Fig-1] [Fig.l] illustrates a rear schematic view of a traction system with rigid bridge according to known art;

[0021] [Fig.2] [Fig.2] illustrates a first embodiment of a traction system electrical modular;

[0022] [Fig.3] [Fig.3] illustrates a second embodiment of a modular traction system;

[0023] [Fig.4] [Fig.4] illustrates a rigid axle traction system comprising a modular traction system according to Figures 2 and 3;

[0024] [Fig.5] [Fig.5] illustrates a rigid bridge traction system comprising an electric modular traction system according to Figures 2 and 3; and

[0025] [Fig.6] [Fig.6] illustrates a traction system with independent wheel suspension comprising an electric modular traction system according to Figures 2 and 3. Detailed description of the invention

[0026] In Figures 2 and 3, an electric traction module 1 is schematically illustrated. Such an electric traction module 1 essentially comprises at least one electric motor 2 and a mechanical transmission system 3 configured to carry the mechanical torque supplied by at least one electric motor 2 to a pair of half-axles 4, 5 of a vehicle 10 each configured to carry, at its end, a wheel, for example the rear wheels of a commercial vehicle, as described in the following part.

[0027] Advantageously, the at least one electric motor 2 and the mechanical transmission system 3 are both housed inside a casing 8 configured to delimit an internal volume 9 suitable for the purpose.

[0028] In the first embodiment, [Fig.2], the electric traction module 1 comprises a single electric motor 2a housed inside the internal volume 9 defined by the carcass 8, connected via the mechanical transmission system 3 to a left half-axle 4 and to a right half-axle 5, configured to carry the respective wheels, as mentioned above.

[0029] The electric motor 2a is sized to provide a torque such that it moves a 3.5 tonne vehicle, therefore capable of providing a power P preferably between 80 kW and 150 kW, in order to provide approximately 5000 Nm of torque to the wheels (total of the two traction wheels).

[0030] The transmission system 3, in the case described, comprises a first toothed wheel 11 carried by an output shaft of the electric motor 2a and coupled with a second toothed wheel 12 carried by an intermediate shaft 13. The intermediate shaft 13 further carries a second toothed wheel 14 cooperating with a differential 15, of known type.

[0031] The differential 15, as is known, provides a pair of output shafts 16, 17 each connected to the respective half-axles 4, 5 by means of a respective homokinetic joint 18, 19, for example a Cardan joint.

[0032] In the second embodiment, [Fig.3], the electric traction module 1 comprises a pair of electric motors 2a, 2b each housed inside a respective internal volume 9a, 9b defined by the frames 8a, 8b. The frames 8a, 8b are advantageously connected integrally to each other.

[0033] The electric motors 2a, 2b are dimensioned to provide, overall, a torque such that it moves a 7-ton vehicle, so each of the axles is capable of providing a power P substantially similar to that of the module of [Fig. 1].

[0034] Overall, the module of [Fig.2] can therefore provide a power equal to 2P, i.e. preferably between 160 kW and 300 kW; corresponding to approximately 10,000 Nm of torque at the wheels. More preferably, the module 1 of [Fig.3] can also include reducers with epicyclic wheels positioned at the output of the half-axles, or the wheels, to then increase the reduction ratio, up to a maximum of 2-3 times. For example, it is possible to obtain torques at the wheels of a value greater than 10,000 Nm, for example for heavy vehicles up to 18 tonnes, it is possible to arrive at torques supplied of the order of 30,000 Nm in total.

[0035] It is therefore possible to provide electric traction modules 1 in which the electric motor 2 and the transmission 3 are configured to provide a power N times P where P is the power of a basic module and N is an integer between 1 and 5.

[0036] In the example described, the mechanical transmission system 3 is separated by each half-axle 4, 5 and comprises a first gear system 20a and a second gear system 20b respectively configured to connect the first and second electric motor 2a, 2b with the half-axle 4, 5.

[0037] In particular, the first gear system 20a may comprise a first toothed wheel 21a carried by an output shaft of the electric motor 2a and coupled with a second toothed wheel 22a carried by an intermediate shaft 23a. The intermediate shaft 23a further carries a second toothed wheel 24a coupled with a toothed wheel 25a carried by an output shaft 16 connected to the left half-axle 4 by means of a respective constant velocity joint 18, for example a cardan joint.

[0038] In a preferably mirror-image manner, the second gear system 20b may comprise a first gear wheel 21b carried by an output shaft of the electric motor 2b and coupled with a second gear wheel 22b carried by an intermediate shaft 23b. The intermediate shaft 23b further carries a second gear wheel 24b coupled with a gear wheel 25b carried by an output shaft 17 connected to the left half-axle 5 by means of a respective constant velocity joint 19, for example a cardan joint.

[0039] The electric traction module 1 can be advantageously associated in a vehicle rear suspension system, as described in the following part.

[0040] With reference to [Fig. 4], a vehicle 100 is illustrated having a chassis 101 suspended, as described in the following part, relative to a rigid bridge assembly 30 according to a first embodiment of such a system.

[0041] The rigid bridge assembly 30 comprises a transverse element 31, substantially a rigid bar, rigidly connecting together a pair of wheels 102, 103 of the vehicle 100. This transverse element 31 is also movably connected to the chassis 101 of the vehicle, advantageously by elastic damping means 104, of known type, such as for example leaf springs or a system with several arms and helical springs.

[0042] The electric traction module 1 is carried by the chassis 101, advantageously integral with the latter, and the half-axles 4, 5 are connected to the wheels 102, 103 in a known manner.

[0043] With reference to [Fig.5], a vehicle 100 is illustrated having a chassis 101 suspended, as described in the following part, relative to a rigid bridge assembly 40 according to a second embodiment of this system.

[0044] The rigid bridge assembly 40 comprises a transverse element 41 rigidly connecting together a pair of wheels 102, 103 of the vehicle 100. This transverse element 41 is also movably connected to the chassis 101 of the vehicle, advantageously by means of elastic damping means 104, of known type, such as for example leaf springs or a system with several arms and helical springs.

[0045] The transverse element 41 further defines a structure resistant to the loads transmitted by the chassis 101 to the latter, avoiding transmission at the same time to the module 1. In the illustrative example described, the intermediate transverse element defines a space 42, axially delimited by two upper and lower parts 41a, 41b of the transverse element 41 and laterally by the end parts and the connection with the wheels 102, 103.

[0046] The electric traction module 1 is advantageously carried by the transverse element 41 inside the volume 42, preferably in a mobile manner.

[0047] Advantageously, the movable connection between the carcass 8 of the electric traction module 1 and the transverse element 41 comprises at least elastic damping means 43 connecting in a movable manner at least vertically, the carcass 8 to the parts 41a, 41b.

[0048] With reference to [Fig.6], a vehicle 100 is illustrated having a chassis 101 suspended relative to its wheels 102, 102, as described in the following part, by means of an independent suspension system 50.

[0049] The independent suspension system 50 is a suspension of known type 51, 52 for each wheel 102, 103 configured to connect the latter to the chassis 101 of the vehicle 100. These suspensions 51, 52 may for example each comprise a plurality of arms 53 and elastic shock-absorbing means 54 connecting the respective wheel 102, 103 to a housing element 55 carried by the chassis, preferably in an integral manner.

[0050] The electric traction module 1 is advantageously carried by the housing element 55, preferably in an integral manner. Preferably, the housing element 55 comprises a flange extending from the chassis 101 towards the ground.

[0051] From the above, the advantages of the electric traction module 1 and the previously described bridge assembly are clear.

[0052] The electric traction module 1 can be used in a modular manner on a variety of vehicles with different types of suspension, independent or with rigid axle.

[0053] In particular, the electric traction module 1 can be sized by different vehicle / tonnage typologies which will modify the number of associated electric motors and / or the transmission typology.

[0054] The electric traction module 1 can be carried by the axle itself, thus overcoming the deadlock, the chassis 1 which can be used on different types of axles.

[0055] As already indicated, the electric traction module 1 can be used on different types of suspensions, of the rigid axle type or with independent suspensions, promoting economies of scale.

[0056] It is finally clear that modifications and variants can be made to the electric traction module 1 and to the bridge assembly produced according to the present invention, which, however, do not depart from the scope of protection defined by the claims.

[0057] As indicated, the number of electric motors and the transmission type may vary depending on the power that the electric traction module 1 must provide.

[0058] Again, different types of suspensions may use the electric traction module 1. For example, the rigid element 41 may define different seats or modes for carrying the electric traction module 1, different from the space 42 described in the present application by way of example.

Claims

Claims

1. A bridge assembly (40) for a heavy vehicle, said bridge assembly (40) comprising a transverse element (41) rigidly connecting together at least one pair of wheels (102, 103), said transverse element (41) defining a space (42) axially delimited by two upper and lower parts (41a, 41b) of the transverse element (41) and laterally by end parts and the connection with the wheels (102, 103), said bridge assembly (40) comprising an electric traction module (1), movably carried by said transverse element (41), inside the space (42), said traction module comprising at least one electric motor (2), a first and a second output shaft (16, 17) and a transmission (3) configured to connect said at least one electric motor (2) with at least one of said first and second output shafts (16, 17),said electric traction module (1) further comprising a carcass (8) configured to define a volume (9) in which said electric motor (2) and said transmission (3) and at least a portion of said first and second output shafts (16, 17) are housed.,

2. An assembly according to claim 1, further comprising a first and a second half-axle (4, 5), said first half-axle (4) being connected to said first output shaft (16) via a first constant velocity joint (18) and said second half-axle (5) being connected to said second output shaft (17) via a second constant velocity joint (19).

3. An assembly according to claim 1 or 2, wherein said module comprises a single electric motor (2a) and wherein said transmission (3) comprises a differential (15) connected to said first and second output shafts (16, 17).

4. An assembly according to claim 1 or 2, wherein said module comprises a first electric motor (2a) and a second electric motor (2b), said transmission (3) comprises a first gear system (20a) connecting said first electric motor (2a) and said first output shaft (16) and a second gear system (20b) connecting said second electric motor (2b) to said second output shaft (17).

5. An assembly according to one of the preceding claims, wherein said transmission (3) comprises epicyclic gears.

6. Assembly according to one of the preceding claims, in which said at least one electric motor has a basic power P of between 80 and 150 kW.

7. An assembly according to claim 6, wherein said at least one electric motor (2) and said transmission (3) are sized to provide a power module equal to N times the base power P, where N is a predetermined integer between 2 and 5.

8. A vehicle (100) comprising a rigid bridge assembly (40) according to any preceding claim.

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