ELECTRIC POWERED VEHICLE WITH MULTIFUNCTIONAL CHARGING CABLE

Description

DESCRIPTION of the industrial invention entitled: “Electric-powered vehicle with multifunction charging cable” by: Stellantis Europe SpA, Italian nationality, Corso Giovanni Agnelli 200, 10135 Turin TO. Designated Inventors: TURI Giovanni Filed on: **** DESCRIPTION TEXT Field of invention The present invention relates to an electric traction vehicle of the type including: - an electric motor; - an electric accumulator, in the form of an electric battery, configured to deliver electrical power at a predetermined voltage to said motor electric and / or to at least one electrical user of the vehicle, wherein said electric accumulator and said electric motor are connected electrically connected to each other by means of connecting cables, - a charging cable. Known technique As is known in the field of electric vehicles, in particular battery powered, a vehicle battery charging phase includes generally electrically connect the vehicle to an external power supply to vehicle, such as a charging station. Among the known solutions, the electrical connection between the vehicle and the external power supply is made by a charging cable supplied with the vehicle which, if necessary, is connected on one side to the vehicle battery and on the other to the external power supply. In more detail, the charging cable has connectors at its ends electrical configured to engage respective pre-arranged connectors on the vehicle and the power supply respectively. Once the battery charging process is finished, the charging cable is decoupled from the external power supply and battery and is generally stored within a compartment of the vehicle, such as a trunk vehicle. Between one battery charging phase and the next, and in particular during the normal operating phases of the vehicle, the charging cable therefore remains unused, resulting in unnecessary weight and bulk inside the vehicle. Therefore, the Applicant proposed to further improve the solutions in this field, in order to create an electric traction vehicle in where the charging cable can be used even when the battery is not in charging phase. Purpose of the invention It is therefore an object of the invention to provide a electric traction vehicle of the type indicated above which is exempt from the drawbacks discussed above. In particular, an object of the invention is to provide a vehicle electric traction, especially battery-powered, where the charging cable can be used even when the battery is not charging. Summary of the invention In order to achieve one or more of the above-mentioned purposes, the invention has for object an electric traction vehicle, in particular battery powered, of the type indicated above and characterised by the fact that the vehicle is configured in such a way such that the charging cable can be selectively arranged in a first configuration in which at least one portion of the charging cable connects together said vehicle's electric accumulator and an external energy supply to the vehicle during the charging phases of said electric accumulator, or in a second configuration, wherein at least a portion of the charging cable is arranged to electrically connect the electric battery and the electric motor, and in which in matching the second configuration of the charging cable, the at least one portion of the charging cable is arranged in parallel with at least one of the cables connection. According to another favorite feature, the charging cable has a modular structure comprising at least two connectable segments electrically in series with each other to define the charging cable, and in which the portion of the charging cable arranged to electrically connect the battery and the electric motor or external power supply to the vehicle includes at least one of the aforementioned segments. According to an additional favorite feature, when the charging cable is arranged in the second configuration, it comprises a first segment and a second segment, the first and second segments being such that the first segment conducts a first current out of the accumulator and into the motor electric, and the second segment conducts a second current out of said electric motor and input to said accumulator Brief description of the figures Further features and advantages of the invention will result from the description that follows with reference to the attached drawings, provided for information purposes only non-limiting example, where: - Figure 1 is a schematic view of the vehicle according to this invention during a charging phase of a vehicle battery, - Figure 2 is a schematic view of a vehicle circuit according to the present invention, - Figures 3A and 3B are schematic views of two connectors of the vehicle according to the present invention, - Figure 4 is a schematic view of a vehicle circuit equivalent to the circuit in figure 2, - Figure 5 is a perspective view of a vehicle compartment according to the present invention. Detailed description of multiple implementation forms In the attached drawings, reference 1 indicates as a whole a vehicle with electric traction according to a preferred embodiment of this invention invention. With particular reference to figures 1 and 2, vehicle 1 comprises, in known in itself, an electric motor 2 configured to transmit a driving torque of the vehicle's wheels, and an electric accumulator 4, preferably an electric battery 4, configured to deliver electric power to one or more electrical users of the vehicle 1. The amount of electrical power supplied by accumulator 4 is evaluated as a function, in particular as sum of the energy demands of the electrical users of vehicle 1. In particular, the electrical consumers of vehicle 1 powered electrically from the accumulator 4 include the electric motor 2 and one or more users auxiliary systems of the vehicle 1, such as on-board electronics or a control system conditioning. More specifically, once the electrical power required by the electrical consumers of vehicle 1, this is supplied by the electric accumulator 4 at a constant voltage value and, therefore, with an output current of continuous type. As is known per se, the electric motor 2 can be either of the type powered by direct current, for example a synchronous motor of the type brushless, both of the type powered by alternating current, so-called brushless motor asynchronous. In the latter case it is necessary to provide an inverter on vehicle 1 (not illustrated) located in an intermediate position between the accumulator 4 and the motor electric 2 and configured to convert the direct current coming from from the alternating current accumulator 4 to be fed to the electric motor 2. Figure 2 shows a portion of an electrical system 6 of vehicle 1 in which schematically represents the electrical connections between the accumulator 4 and the electric motor 2. In particular, the electrical system 6 comprises a first circuit 8 arranged upstream of the electric motor 2 and including at least one cable connection 10 configured to conduct an output current I10 from accumulator 4 and into electric motor 2. The electrical system 6 also includes a second circuit 12 arranged downstream of the electric motor 2 and including at least one connection cable 14 configured to conduct a current I14 out of the electric motor 2 and in input to accumulator 4. Still referring to figure 2, the arrangement of the cables connection 10, 14 inevitably results in the presence of additional loads electrical system 6 represented by the internal impedances of the cables connection 10, 14 indicated with the references Z10, Z14. With particular reference to figure 1, vehicle 1 also comprises, a charging cable 16 configured to electrically connect the vehicle to each other 1 and an energy supply 18 external to the vehicle, for example a column of charging 18, during a charging phase of the electric accumulator 4. In particular, the charging cable 16 has at its ends two electrical connectors 20, 22 which, during the charging phase of the accumulator 4, are connected to respective connectors located on vehicle 1 and on the external power supply 18. In a preferred embodiment of the present invention, the connectors 20, 22 are made according to the IEC 62196 standard which uses electrical connectors of the type illustrated schematically in figures 3A, 3B. For example, the charging phase of the electric battery 4 performed in accordance with the IEC 62196 standard includes a supply of electrical power from the external power supply 18 equal to a value in the range 3kW – 50kW and transferred by means of a current three-phase alternating current with a peak value of 63A and a voltage of 480V. Of course, the charging modes of the electric accumulator 4 They can be of any other known type. For example, the IEC standard itself 62196 also provides for a battery recharge 4 which uses the transfer of electrical power using direct current, for example 140A, at a voltage value approximately equal to 500V. In particular, the connector 20 illustrated in Figure 3A is a male type comprising a pinout 24, wherein each pin of the connector 20 is associated with a charging cable cable 16. In more detail, pinout 24 includes: - three pins 26 associated with respective cables (not illustrated) configured for conduct the three phases of the electric current supplied by the external power supply 18; - a pin 28 associated with a neutral wire; - a pin 30 associated with a ground wire; - two pins 32 associated with respective control cables connectable to the terminals of an activation circuit (not shown). In summary, the charging cable 16 comprises five conductor cables suitable for make the electrical connection between battery 4 and the external power supply 18, and two control cables associated with the activation circuit. In particular, the activation circuit is configured to control the correct connection of connector 20 to vehicle 1 or power supply 18 and for, following a positive outcome of the aforementioned control, allow a passage of current through the wires associated with pins 26, 28, 30. Connector 22 shown schematically in figure 3B is a female electrical connector substantially similar to connector 20 described with reference to figure 3A, which is distinguished from the latter by the made up of pads 34, 36, 38, 40 associated with respective cables and configured to be coupled to the corresponding pins 26, 28, 30, 32 of the connector 20. With reference to figure 2, the vehicle connector 1 is designed to receive one end of the charging cable 16 during the battery charging phase 4, and therefore also analogous to one of the connectors 20, 22 described above, is electrically connected to the accumulator 4 by means of an additional cable connection 42 of the electrical system 6 of the vehicle 1. As anticipated at the beginning of this description, once finished the charging phase of the accumulator 4, the charging cable 16 is disconnected from the vehicle 1 and the external power supply 18, and is stored inside a compartment 44 of the vehicle 1, for example a trunk 44 (figure 5), until the next stage of battery charging 4. With reference to figures 2 and 5, vehicle 1 according to this The invention is equipped with electrical connectors, similar to connectors 20, 22 described above and to which the same references are attributed, arranged within the compartment 44 of vehicle 1 and accessible from the outside, for example by an operator or from a vehicle user 1. In more detail, the vehicle 1 comprises at least a first connector 20, 22 permanently electrically connected to the accumulator 4 and a second connector permanently electrically connected to the electric motor 2. In one embodiment of the present invention, vehicle 1 comprises a first pair 46 of connectors 20, 22 associated with the circuit 8 of the electrical system 6 arranged upstream of the electric motor 2, and a second pair 48 of connectors 20, 22 associated with circuit 12 of electrical system 6 located downstream of the electric motor 2. In the embodiment considered, when the charging cable 16 is not used for charging the battery 4 and, therefore, is located inside the compartment 44, and more generally during the normal operating phases of vehicle 1, the connectors 20, 22 carried by the charging cable 16 can be advantageously connected to respective connectors 20, 22 of one of the aforementioned pairs of connectors 46, 48 of vehicle 1, thus realizing a additional electrical connection between the accumulator 4 and the electric motor 2. In one example, connect connectors 20, 22 of the charging cable 16 to the respective connectors 20, 22 of the first pair of connectors 46 of vehicle 1 results in an additional electrical connection between the accumulator 4 and the motor electric 2 arranged in parallel with respect to the electrical connection made by the connection cable 10 normally arranged. According to a particularly advantageous feature of the present invention, the charging cable 16 has a modular structure such that it comprises at least a first segment 50 and at least a second segment 52 electrically connectable to each other in series to form the charging cable 16. In the preferred embodiment illustrated in the figures, the charging cable 16 consists of the first and second segments 50, 52; however, they are not excluding embodiments where the charging cable 16 comprises a number any of segments that can be connected to each other in series. For example, the 16 charging cable has a length total of six meters and includes two segments 50, 52, each having a length equal to three meters. In particular, each segment has two ends on it connectors so that the series connection between two segments 50, 52 subsequent charging cable 16 is obtained by coupling reciprocal of a first connector carried on one end of the first segment 50 and a second connector carried on one end of the second segment 52 adjacent to the end of the first segment 52. In a preferred embodiment, the electrical connectors that realize the series connection between two or more segments 50, 52 of the charging cable 16 are of the same typology as the connectors 20, 22 described above and, therefore, they are associated with the same references in the figures. It is therefore evident that the modular structure of the charging cable 16 allows you to use only one of the segments 50, 52 and to connect two in series or more segments of the charging cable 16 depending on the operator's needs or of the vehicle user 1. In particular, in the case in which during the battery charging phase 4 the vehicle 1 is placed at a distance from the external power supply 18 very less than the entire extension of the 16 charging cable, it is possible connect the power supply 18 and the battery 4 together by means of a portion 54 of the charging cable 16 comprising a single segment 50, 52 or two or more segments 50, 52 connected in series with each other. Also, when the 16 charging cable is not used for charging of the accumulator 4 and, therefore, is arranged within the compartment 44, and more generally During normal vehicle operation phases 1, it is possible to connect electrically connect the accumulator 4 and the electric motor 2 to each other by means of a portion 56 of the charging cable 16 comprising a single segment 50, 52 or two or more segments 50, 52 connected in series with each other. In other words, vehicle 1 is configured so that the cable reload 16 can be selectively arranged in a first configuration in which a portion, e.g. portion 54, of the charging cable 16 connects electrically between each other the electric accumulator 4 and the external power supply 18 during the charging phase of accumulator 4, or in a second configuration wherein a portion, e.g. portion 56, of the charging cable 16 connects electrically connect the accumulator 4 and the electric motor 2 to each other. In a preferred embodiment of the present invention and with Refer to figures 2 and 5, when the charging cable 16 is used for electrically connect the accumulator 4 and the electric motor 2, the first segment 50 electrically connects the electric accumulator 4 and the motor electric 2 so as to conduct a current I50 out of the accumulator 4 and at the input of the electric motor 2. In more detail, the electrical connectors 20, 22 brought to the ends of the first segment 50 are electrically connected to the respective connectors 20, 22 of the first pair of connectors 46 of vehicle 1. In a completely analogous way, the second segment 52 electrically connects the electric accumulator 4 and the electric motor 2 so as to drive a current I52 output from electric motor 2 and input to accumulator 4. In this case, the electrical connectors 20, 22 brought to the ends of the second segment 52 are electrically connected to the respective connectors 20, 22 of the second pair of connectors 48 of vehicle 1. In the embodiment considered, the first segment 50 and the second segment 52 of the charging cable 16, each characterized by having a internal impedance value Z50, Z52, are, therefore, arranged in parallel with the connecting cables 10, 14 respectively of the first circuit 8 and of the second circuit 12 of the electrical system 6 of the vehicle 1. More in detail, when segments 50, 52 are arranged to connect electrically the accumulator 4 and the electric motor 2, the respective currents I50, I52 are conducted by the three conductor cables, by the neutral cable and using the ground wire associated with pins 26, 28, 30 or corresponding pads 34, 36, 38 of connectors 20, 22. In other words, the three conductor cables, the neutral cable and the earthing cable ground of each segment 50, 52, for a total of five conductor cables, which during the charging phase of the accumulator 4 they perform specific functions of known in themselves from the IEC 62196 standard, in this example they are used as an electrical conductive material between the accumulator 4 and the electric motor 2. Figure 4 schematically illustrates an equivalent electrical system 58 to the electrical system 6 in the configuration in which the first segment 50 of the cable charging cable 16 was arranged in parallel to the connection cable 10 of the first circuit 8, and wherein the second segment 52 of the charging cable has been arranged in parallel to the connecting cable 14 of the second circuit 12. In the equivalent diagram 58, the parallel connection between the first segment 50 and the connecting cable 10 is equivalent to a cable of connection 60 configured to conduct an output current I60 from accumulator 4 and into electric motor 2. Advantageously, the 60-gauge connecting cable has an impedance equivalent Z60 characterized by having a lower value than to the impedance Z10 of the connecting cable 10 or to the impedance Z50 of the first segment 50 considered individually. In a completely analogous way the parallel connection between the second segment 52 and the connecting cable 14 is equivalent to a cable of connection 62 configured to conduct a current I62 out of the motor electric 2 and input to accumulator 4. Here too, the connecting cable 62 has an impedance equivalent Z62 characterized by having a lower value than to the impedance Z14 of the connecting cable 14 or to the impedance Z52 of the second segment 52 considered individually. According to a further feature of the vehicle 1 according to this invention, the vehicle compartment 44 comprises at least one arrangement 63 of restraining elements 64 attached to the vehicle 1 and configured to restrain in position a respective segment 50, 52 of the charging cable 16 when it is stored in compartment 44. In particular, each provision 63 includes a plurality of 64 retaining elements arranged in a predetermined pattern in such as to hold in position respective sections of the segment 50, 52 of the charging cable 16 along the entire length of it, thus avoiding a possible kinking or damage to segment 50, 52. In one or more embodiments, each arrangement 63 of elements of holding 64 may be such that when segments 50, 52 are received in compartment 44, they reproduce any shapes and / or geometries, for example a logo. The following description summarizes the procedure of using the vehicle charging cable 16 1. In a first phase, corresponding to a condition in which the electric battery 4 is discharged and the vehicle 1 is positioned in proximity of an external power supply 18, such as a charging column 18, the operator or the user of vehicle 1 extracts the charging cable 16 stored in the compartment 44 of the vehicle 1. Subsequently, the operator determines as a function of a distance of the vehicle 1 from external power supply 18, how many segments 50, 52 of the cable recharge 16 is necessary to connect in series to form a portion 54 of the charging cable 16 to electrically connect the battery 4 to the power supply 18 (note that the portion 54 of the charging cable 16 may be consisting of a single segment 50, 52, as well as the entire charging cable 16). At this stage, the connectors 20, 22 arranged at the ends of the portion 54 are connected respectively to an electrical connector located on the vehicle 1 and to an electrical connector located on the external power supply 18. Once the charging phase of accumulator 4 is finished, portion 54 is decoupled from the vehicle 1 and the external power supply 18 and is placed back into compartment 44 of vehicle 1. In more detail, the charging cable 16 is repositioned inside the compartment 44 downstream of the charging phase of the accumulator 4 so that the connectors 20, 22 of the ends of at least one portion 56 of the charging cable 16 are electrically connected to a respective pair 46, 48 of connectors 20, 22 of the vehicle so as to create an electrical connection between the accumulator 4 and the electric motor 2 arranged in parallel with one of the connecting cables 10, 14 of the electrical system 6. In the preferred embodiment, when the charging cable 16 is stored within compartment 44 of vehicle 1, the first segment 50 and the second segment 52 are arranged respectively in parallel to the cable connection 10 of circuit 8 and in parallel to the connection cable 14 of the circuit 12. As is evident from the above description, a feature fundamental aspect of the present invention lies in the fact that the vehicle 1, thanks to to the pairs of connectors 46, 48 arranged in the compartment 44, is configured in such a way such that the charging cable 16 can also be used during normal vehicle operation 1 and not only during the charging phase of accumulator 4. In particular, thanks to this feature, the charging cable 16, which otherwise it would be unused during normal operation of the vehicle 1 representing an unnecessary weight and bulk inside compartment 44, it can be used to improve the performance of the electric motor 2. In fact, with particular reference to the equivalent circuit 58 illustrated in the figure 4, the voltage imposed by the accumulator 4 is balanced by the voltage drops voltage at impedances Z60, Z62 and electric motor 2, which represent the circuit loads. In particular, the pressure drop due to to the impedances of the electrical system 6 is directly proportional to the value of the impedance. It is therefore evident that the provision of electrical connections between the electric accumulator 4 and the electric motor 2 in addition to the cables connection 10, 14 normally arranged in the electrical system 6, so such that the equivalent impedances Z60, Z62 have a lower value than to the corresponding impedances Z10, Z14 of the individual connecting cables 10, 14, allows to reduce pressure losses along the electrical connections of the system electric 6 and, therefore, to increase the voltage available at the motor terminals electric 2. In other words, the power absorbed by the loads is proportional to the impedance of the load and the square of the current conducted through it it, a reduction of the impedances of the electrical system 6 results, with the same power supplied by the accumulator 4, in a lower power dissipated in correspondence of the electrical connections between the accumulator 4 and the engine electric 2 and in a greater power available to be supplied to the engine 2. A further advantage of the present invention is related to the structure modular charging cable 16, which allows you to use just one portion 54, 56 of the charging cable 16 depending on the operator's needs or vehicle user 1. For example, in the case where the electric battery 4 of the vehicle 1 has to be recharged, and vehicle 1 is placed at a distance from the power supply external 18 such as to require a shorter electrical connection than the Total length of the charging cable 16, you can use only one of segments 50, 52 or a series combination of them, resulting in a cable less bulky and less heavy to handle. Naturally, without prejudice to the principle of the invention, the details of construction and forms of implementation may vary widely from as described and illustrated purely by way of example, without thereby departing from the scope of the present invention.

Claims

1. Electric vehicle (1) comprising: - an electric motor (2); - an electric accumulator (4), in the form of an electric battery (4), configured to supply electric power at a predetermined voltage to said electric motor (2) and / or to at least one electrical user of the vehicle (1), wherein said electric accumulator (4) and said electric motor (2) are electrically connected to each other by means of connection cables (10, 14), - a charging cable (16), characterised in that the vehicle (1) is configured in such a way that said charging cable (16) can be selectively arranged in a first configuration in which at least a portion (54) of the charging cable (16) connects said electric accumulator (4) of the vehicle (1) and an energy supply (18) external to the vehicle (1) during the charging phases of said electric accumulator (4), or in a second configuration,wherein at least one portion (56) of said charging cable (16) is arranged so as to electrically connect said electric accumulator (4) and said electric motor (2), wherein in correspondence with said second configuration of the charging cable (16), said at least one portion (56) of the charging cable (16) is arranged in parallel with at least one of said connection cables (10, 14)., 2. Vehicle according to claim 1, wherein said charging cable (16) has a modular structure comprising at least two segments (50, 52) electrically connectable in series with each other to define said charging cable (16), and wherein said portion (54, 56) of the charging cable (16) arranged to electrically connect said accumulator (4) and said electric motor (2) or said external power supply (18) to the vehicle (1) comprises at least one of said segments (50, 52).

3. Vehicle according to claim 2, wherein, when said charging cable (16) is arranged in said second configuration, it comprises a first segment (50) and a second segment (52), said first and second segments (50, 52) being such that said first segment (50) conducts a first current (I50) out of said accumulator (4) and into said electric motor (2), and said second segment (52) conducts a second current (I52) out of said electric motor (2) and into said accumulator (4).

4. Vehicle according to claim 2, wherein each segment (50, 52) of said charging cable (16) comprises conductive cables suitable for making the electrical connection between said accumulator (4) and said electric motor (2) or said power supply (18) external to the vehicle (1), and at least two control cables associated with an activation circuit, said activation circuit being configured to regulate the passage of electric current through said conductive cables.

5. Vehicle according to claim 2, wherein each segment (50, 52) of said charging cable (16) carries at its free ends a first electrical connector (20, 22) and a second electrical connector (20, 22), said first and second electrical connector (20, 22) being couplingable with each other so as to achieve the series connection of two or more segments (50, 52) of said charging cable (16).

6. Vehicle according to claim 5, comprising a compartment (44) configured to receive at least one of said segments (50, 52) of the charging cable (16), said compartment (44) comprising at least one pair (46, 48) of electrical connectors (20, 22) associable with a respective segment (50, 52) of the charging cable (16), - 15 said at least one pair (46, 48) of electrical connectors (20, 22) of the compartment (44) including: - a first electrical connector (20, 22) electrically connected to said electric accumulator (4) of the vehicle (1) and configured to be coupled to the first electrical connector (20, 22) of the respective segment (50, 52), - a second electrical connector (20, 22) electrically connected to said electric motor (2) of the vehicle (1) and configured to be coupled to the second electrical connector (20, 22) of the respective segment (50, 52), 22) of the respective segment (50, 52).

7. Vehicle according to claim 6, wherein said compartment (44) comprises at least one arrangement (63) of retaining elements (64) configured to retain in position a respective segment (50, 52) of said charging cable (16) received within said compartment (44), said retaining elements (64) being preferably configured in such a way that when the respective segment (50, 52) is received in the compartment (44), it reproduces any shapes and / or geometries, for example a logo.

8. Method of using a charging cable (16) of an electric vehicle (1), wherein the vehicle comprises: - an electric motor (2); - an electric accumulator (4), in the form of an electric battery (4), configured to supply electric power at a predetermined voltage to said electric motor (2) and / or to at least one electric user of the vehicle, wherein said electric accumulator (4) and said electric motor (2) are electrically connected to each other by means of connection cables (10, 14), the method comprising: - in a phase of charging of said electric accumulator (4) of the vehicle (1), electrically connecting together said electric accumulator (4) and an energy supply (18) external to the vehicle (1) by means of at least a portion (54) of said charging cable (16), - when the vehicle is not in a phase of charging of said electric accumulator (4),electrically connect said electric accumulator (4) and - 16 - said electric motor (2) to each other by means of at least one portion (56) of said charging cable (16), said at least one portion (56) of the charging cable (16) being arranged in parallel with at least one of said connecting cables (10, 14)., 9. Method of using a charging cable according to claim 8, characterised in that the vehicle is equipped with a first electrical connector (20, 22) permanently electrically connected to said electric accumulator (4) of the vehicle (1) and a second electrical connector (20, 22) permanently electrically connected to said electric motor (2) of the vehicle (1), and that the operation of electrically connecting said electric accumulator (4) and said electric motor (2) together by means of said at least one portion (56) of said charging cable (16) is performed by connecting end connectors (20, 22) of said at least one portion (56) of said charging cable (16) respectively with said first electrical connector (20, 22) and second electrical connector (20, 22).

10. Method of using a charging cable according to claim 8, wherein said charging cable (16) has a modular structure comprising at least two segments (50, 52) electrically connectable in series with each other so as to define said charging cable (16), and wherein said step of electrically connecting together said electric accumulator (4) and said energy supply (18) comprises determining a number of segments (50, 52) of said charging cable (16) to be connected in series with each other so as to form said at least one portion (54) of the charging cable (16) as a function of a distance of the vehicle (1) from said energy supply (18).

11. Method of using a charging cable according to claim 8, wherein said charging cable (16) is a modular structure comprising at least two segments (50, 52) electrically connectable in series with each other so as to define said charging cable (16), - 17 wherein said step of electrically connecting together said electric accumulator (4) and said electric motor (2) by means of at least one portion (56) of said charging cable (16) comprises: - arranging a first segment (50) of said charging cable (16) in parallel with a first connection cable (10) in such a way that said first segment (50) conducts a first current (I50) out of said accumulator (4) and in to said electric motor (2),- arrange a second segment (52) of said charging cable (16) in parallel to a second connection cable (14) in such a way that said second segment (52) conducts a second current (I52) out of said electric motor (2) and into said accumulator (4).,