Traction motor of a vehicle

Abstract

The present invention relates to a traction motor for a vehicle. The traction motor for a vehicle comprises: a stator (1); a rotor (3) which is designed to rotate relative to the stator (1) at a speed w3 greater than 5000 rpm under the action of the electrical energy fed to the motor; a fan (5) which is designed to rotate relative to the stator (1) at a speed w5 to ventilate the motor; a magnetic reduction device (7) by means of which the rotor (3) drives the fan (5) to rotate, the magnetic reduction device (7) being designed to transmit the rotation of the rotor (3) to the fan (5) with a reduction ratio [Formula 5] R = w5 / w3. In order for the self-ventilating motor to be particularly quiet at high speeds, the absolute value of the reduction ratio R is less than or equal to 0.85, preferably equal to approximately 0.5.

Description

Technical Field

[0001] The present invention relates to a traction motor for a vehicle and to a railway vehicle comprising such a motor (moteur).

[0002] The present invention pertains to the field of electrically or hybrid-powered traction vehicles, and more particularly to railway vehicles with electric traction such as trains, trams or subways.

Background Art

[0003] It is known to produce trains whose propulsion is ensured by a number of self-ventilated motors. Each motor includes a rotor and a stator, and a fan (ventilateur) fixed to the end of the rotor shaft. Thus, when the rotor rotates relative to the stator, the fan ventilates the motor to cool it. This makes it possible to ensure that the motor is necessarily ventilated during operation, thereby ensuring its own ventilation, where the ventilation propeller is directly actuated by the rotor. It is provided, for example, that the motor is an asynchronous motor with a nominal power of approximately 450 kW (kilowatts). Asynchronous motors are typically designed to reach a maximum rotor speed of approximately 4500 rpm (revolutions per minute). Thus, this type of motor is likely to weigh, for example, approximately 700 kg (kilograms).

[0004] Considering energy efficiency, it is provided to equip new trains with motors having a higher speed, in order to obtain a better power / mass ratio. For example, an asynchronous motor with a nominal power of approximately 450 kW and designed to reach a maximum speed of 10,000 rpm can weigh approximately 400 kg, that is, the mass is reduced by approximately 300 kg at equal power compared to the motor provided to operate at 4500 rpm.

[0005] It is necessary to provide a ventilation device for these high-speed motors. However, due to the high speed, providing a ventilation propeller fixed to the rotor generates a lot of noise during use. In addition, providing a ventilation device that is mechanically independent of the rotor is more complex and does not guarantee that ventilation necessarily occurs when the rotor rotates.

[0006] The present invention aims in particular to solve the above-mentioned drawbacks of the prior art and aims to propose a new traction motor for a vehicle that is self-ventilated and particularly quiet when its rotor rotates at high speed.

Summary of the Invention

[0007] The subject of the present invention is a traction motor for a vehicle, the motor comprising: a stator; a rotor designed to rotate about the main axis of the motor relative to the stator at a speed w3 greater than 5000 rpm under the action of an electrical energy feed to the motor; a fan designed to rotate about the main axis relative to the stator at a speed w5 to ventilate the motor; a magnetic reduction device by means of which the rotor drives the fan to rotate, the magnetic reduction device being designed to transmit the rotation of the rotor to the fan with a reduction ratio [Formula 5] R = w5 / w3. According to the invention, the absolute value of the reduction ratio R is less than or equal to 0.85, preferably equal to approximately 0.5.

[0008] The idea on which the present invention is based is to make the rotation of the fan subordinate to the rotation of the rotor by means of a magnetic reduction device in order to obtain self-ventilation of the motor by the fan, the fan rotating at a speed lower than that of the rotor. Thus, the noise of the motor when the rotor rotates at high speed is reduced. The magnetic reduction device itself is silent, especially compared with a mechanical reduction device having a gear train. In addition, the magnetic reduction device has high mechanical efficiency, is easy to adapt to an existing motor, and is easy to maintain because it especially does not require lubrication.

[0009] According to other advantageous features of the invention, the features are taken alone or in combination:

[0010] - The magnetic reduction device comprises: an inner ring fixed relative to the rotor, which comprises a plurality of separate permanent magnets distributed around the main axis and constituting a number p1 of pole pairs; an intermediate ring, which comprises a number n2 of separate ferromagnetic parts distributed around the main axis; and an outer ring, which comprises a plurality of separate permanent magnets distributed around the main axis and constituting a number p3 of pole pairs; a stator ring selected from the intermediate ring and the outer ring is fixed relative to the stator; and a drive ring selected from the intermediate ring and the outer ring and different from the stator ring at the same time is fixed relative to the fan.

[0011] - The magnetic reduction device is configured such that the quantities p1, n2 and p3 satisfy the following relationship: [Formula 1] n2 = p1 + p3.

[0012] - The outer ring is a drive ring fixed relative to the fan; the intermediate ring is a stator ring fixed relative to the stator; and the reduction ratio is written [Formula 4] where, [Formula 2]

[0013] - The outer ring is a stator ring fixed relative to the stator; the intermediate ring is a drive ring fixed relative to the fan; and the reduction ratio is written [Formula 3] where, [Formula 2]

[0014] - The stator includes: a housing, which is penetrated by the rotor along the main axis and contains induction means and an armature belonging to the electric motor; and a flange, which is attached to the housing and is provided with an air circulation opening penetrated by the main axis; and a fan is arranged along the main axis outside the housing, between the housing and the flange, and is configured such that ventilation air circulates through the air circulation opening to ventilate the electric motor.

[0015] - A magnetic deceleration device is arranged along the main axis between the fan and the flange; and the stator coil is fixed relative to the stator by being attached to the stator via the flange.

[0016] - A magnetic deceleration device is arranged along the main axis between the housing and the fan; and the stator coil is fixed relative to the stator by being attached to the stator via the housing.

[0017] - The rotor includes a rotor shaft coaxial with the main axis, which rotates at a speed w3 when the rotor rotates at a speed w3, and supports the fan by means of rolling bearings, and the fan can rotate relative to the rotor about the main axis.

[0018] The subject matter of the present invention is also a railway vehicle, which includes an electric motor as defined above, and the electric motor ensures the traction of the railway vehicle.

Description of the Drawings

[0019] The present invention will be better understood by reading the following description, which is given only as a non-limiting example and with reference to the drawings, in which:

[0020] Figure 1 is a schematic partial longitudinal sectional view of an electric motor according to a first embodiment of the present invention;

[0021] Figure 2 is a schematic partial longitudinal sectional view of an electric motor according to a second embodiment of the present invention;

[0022] Figure 3 is a schematic partial longitudinal sectional view of an electric motor according to a third embodiment of the present invention;

[0023] Figure 4 is a schematic partial longitudinal sectional view of an electric motor according to a fourth embodiment of the present invention; and

[0024] Figure 5 is a schematic front view of a magnetic deceleration device that the electric motor in the previous figures can be equipped with.

Detailed Description

[0025] Regarding the first embodiment, Figure 1 shows the traction electric motor of the vehicle, that is, the electric motor that drives the vehicle to travel alone or in cooperation with other electric motors.

[0026] The vehicle involved is preferably a railway vehicle, which includes one or more electric motors as shown in Figure 1 . The railway vehicle can be a train, such as a high-speed train, or a tram or a subway. As a variant, the electric motor can be used for non-railway vehicles, such as road vehicles.

[0027] The electric motor mainly includes a stator 1, a rotor 3, a fan 5 and a magnetic deceleration device 7. These elements are partially shown in Figure 1 . The electric motor defines a main axis X1, and the main axis X1 is fixed relative to the stator 1.

[0028] The stator 1 is the fixed part of the electric motor, which is provided to be attached to the chassis of the vehicle. The rotor 3 is provided to be mechanically coupled to the wheels of the vehicle so as to drive their rotation, thereby making the vehicle travel.

[0029] The stator 1 includes: a housing 11, which is penetrated by the axis X1; and a stator coil 12, which is completely accommodated inside the housing 11 and advantageously has an annular shape coaxial with the axis X1. The stator coil 12 constitutes the induction device of the electric motor here. The stator 1 is attached to the chassis of the vehicle by means of the housing 11.

[0030] For example, the housing 11 includes a rear wall 16 penetrated by the axis X1. The wall 16 optionally includes an opening centered on the axis X1. The housing 11 advantageously includes a front wall 17, which is penetrated by the axis X1 and has an opening centered on the axis X1. The housing 11 advantageously includes a peripheral wall 19 having an annular shape coaxial with the axis X1, which connects the front wall 17 to the rear wall 16 to enclose the housing 11.

[0031] The stator 1 preferably includes a flange 13, which is provided outside the housing 11, advantageously on the side of the front wall 17. The flange 13 has, for example, an annular shape coaxial with the axis X1, which is in the shape of a ring here, so as to be provided with an opening 14 for the circulation of ventilation air 23. The opening 14 is advantageously centered on the axis X1 and penetrated by the axis X1.

[0032] The stator 1 preferably includes a skirt 15 having an annular shape coaxial with the axis X1, which extends from the flange 13 in the direction of the rear wall 16.

[0033] Preferably, the flange 13 and the skirt 15 (if provided) are fixedly attached to the housing 11 while being spaced from the walls 17 and 19 by any suitable means, including, for example, fixing claws. The outer wall of the stator 1 formed by the flange 13 and the skirt 15 and the inner wall of the stator 1 formed by the walls 17 and 19 of the housing 11 advantageously form a double skin, and an annular duct 21 is provided therebetween, which starts from the opening 14 and terminates at an annular opening 20 formed around the wall 19 at the opposite end of the skirt 15. During use, the ventilation air circulates in the annular duct 21 along the arrow depicting the ventilation air 23 from the opening 14 to the opening 20 to ventilate the electric motor, in particular the contents of the housing 11, especially the stator coils 12. Here, the opening 14 is the air inlet, and the opening 20 is the air outlet.

[0034] The rotor 3 is rotatable relative to the stator 1 about the axis X1.

[0035] Preferably, the rotor 3 includes a rotor shaft 31 coaxial with the axis X1.

[0036] The rotor 3 advantageously passes through the housing 11 along the axis X1 since the rotor shaft 31 passes through the housing 11 through an opening formed at least through the wall 17. Thus, the axial end 33 of the shaft 31 projects from the housing 11 through the wall 17. Preferably, the end 33 does not extend beyond the flange 13.

[0037] Here, the shaft 31 also passes through an opening formed by the wall 16. Thus, the axial end 34 of the shaft 31 projects from the housing 11 through the wall 16.

[0038] The rotor shaft 31 is supported by the housing 11 so as to be rotatable relative to the housing 11 about the axis X1. For this purpose, for example, the opening in the wall 17 includes a rolling element bearing 25 centered on the axis X1. If the shaft 31 also passes through the wall 16, especially through the above-mentioned opening in the wall 16, then the opening also includes a rolling element bearing 24 centered on the axis X1. Each of the bearings 24 and 25 supports the shaft 31 relative to the housing 11 while allowing rotation about the axis X1. The rotation of the vehicle wheels is actuated by the rotor via the shaft 31.

[0039] Depending on the type of the electric motor, the rotor 3 includes rotor permanent magnets, rotor coils, or a rotor frame, which is fixed relative to the shaft 31 by being mounted around the shaft 31. The rotor permanent magnets, rotor coils, or rotor frame constitute the armature 32 of the electric motor. Here, the electric motor is preferably a permanent magnet motor, such that the rotor armature is the rotor permanent magnets. Preferably, a permanent magnet synchronous motor is selected. As a variant, an asynchronous motor or other types of electric motors can be selected.

[0040] The armature 32 is entirely disposed inside the housing 11, centered on the axis X1, and is radially surrounded by the stator coil 12. When electrical energy is fed to the motor, the stator coil 12 is fed with electrical energy, which causes the rotor armature 32 to rotate about the axis X1 relative to the stator coil 12. In the case where the rotor coil forms the rotor armature 32, it may also be necessary to feed electrical energy to the rotor armature 32 in order to cause rotation.

[0041] More generally, feeding power to the motor causes the rotor 3 to rotate about the axis X1 relative to the stator 1.

[0042] The motor is designed to cause the rotor 3 to rotate about the axis X1 relative to the stator 1 at a speed w3 during the nominal use of the motor, or for the use of the motor at cruising speed, which speed may be referred to as the "nominal speed". The speed w3 is preferably equal to approximately 10,000 rpm. This speed w3 is achieved by continuously feeding electrical energy to the motor under the traction load of the vehicle. This motor may be referred to as a high-speed traction motor. More generally, it is specified that the speed w3 is greater than 5000 rpm, and preferably greater than 9000 rpm.

[0043] When the rotor 3 is at the speed w3, the shaft 31 and the armature 32 are also at this speed w3.

[0044] It is also specified that the stator 1 and the rotor 3 are advantageously designed such that the power of the motor is between 50 kW and 2000 kW, preferably between 100 kW and 1000 kW. Preferably, it is specified that the power is greater than 500 kW. This is the nominal mechanical power exhibited by the motor.

[0045] Advantageously, the motor drives the vehicle wheels through the end 34 in order to travel, and the end 34 is connected to the wheels by a mechanical transmission or any suitable device.

[0046] As Figure 1 shown, the fan 5 forms a ventilation wheel, which includes, for example, blades. In the example shown, it is specified that the fan 5 forms a centrifugal ventilation wheel.

[0047] The fan 5 is preferably mounted on the end 33 of the shaft 31 by a bearing 37, preferably a rolling element bearing. Thus, the fan 5 can rotate about the axis X1 relative to the rotor 3 and thus relative to the stator 1. Axially, the fan 5 is preferably disposed between the flange 13 and the housing 11, particularly the wall 17 of the housing 11, as Figure 1 shown, such that the fan 5 is protected against the outside by the flange 13.

[0048] When the fan 5 rotates relative to the stator 1, the fan 5 causes the ventilation air 23 to circulate along the arrow depicting the ventilation air 23. Thus, the rotation of the fan 5 ventilates the electric motor, in particular the housing 11, to cool it. In this example, the ventilation air is axially sucked in by the fan 5 through the opening 14, and the fan discharges the air radially (relative to the end 33 of the shaft 31) into the portion of the duct 21 defined by the wall 17 and the flange 13. Then the ventilation air is guided in the axial direction, along the housing 11, through the portion of the duct 21 defined by the wall 19 and the skirt 15, until the opening 20.

[0049] When the rotor 3 rotates at a speed w3, the rotor 3 drives the fan 5 to rotate about the axis X1 relative to the stator 1 at a rotational speed w5 by means of the magnetic reduction device 7. Thus, the electric motor can be called a "self-ventilated" electric motor.

[0050] In order to reduce the generated noise, in the context of a high-speed electric motor, the reduction device 7 is configured to rotate the fan 5 at a speed w5 lower than the speed w3 of the rotor. For this purpose, it is provided that the reduction device 7 transmits the rotation of the rotor 3 to the fan 5 with a reduction ratio R = w5 / w3, the absolute value of which is less than or equal to 0.85, or even equal to 0.5. When the absolute value of the reduction ratio R is 0.5, the fan 5 rotates at half the speed of the rotor 3 in the same or opposite direction of rotation, which significantly reduces the generated noise, while the speed w3 is greater than 5000 rpm, and especially if the speed w3 reaches 10000 rpm.

[0051] As Figure 1 and Figure 5 shown, the magnetic reduction device 7 advantageously includes an inner ring 71, an intermediate ring 72 and an outer ring 73. These three rings 71, 72 and 73 are coaxial with the axis X1. The inner ring 71 is radially surrounded by the intermediate ring 72 and the outer ring 73. The intermediate ring 72 radially surrounds the inner ring 71 and is radially surrounded by the outer ring 73. The outer ring 73 radially surrounds the inner ring 71 and the intermediate ring.

[0052] For Figure 1 the embodiment, the reduction device 7 is arranged between the housing 11, in particular the wall 17, and the fan 5. Then, the fan 5 covers the reduction device 7 and protects it against the outside, in particular any metal dust that the ventilation air flow might blow away.

[0053] More generally, it is provided that the reduction device 7 and the fan 5 are advantageously outside the housing 11, which facilitates their installation and maintenance. With this particular arrangement, it is also easy to modify a pre-existing electric motor by adding the fan 5 and the reduction device 7 to the free end of the rotor shaft.

[0054] The inner ring 71 is fixed relative to the rotor 3, here mounted by being fixed to the shaft 31. In particular, the ring 71 is fixed to the end 33, preferably fixed between the bearings 25 and 37. Thus, the rotational speed of the inner ring 71 is equal to the speed w3.

[0055] As Figure 5 best seen in, the inner ring 71 includes a plurality of separate permanent magnets 74, which are regularly distributed around the main axis X1. The number of the permanent magnets 74 and their arrangement define the number of pole pairs p1 of the inner ring 71. In Figure 5 the example shown, the magnets 74 are even in number and define an alternation of positive and negative poles around the axis X1, such that the number of pole pairs p1 is 5.

[0056] The outer ring 73 includes a plurality of separate permanent magnets 76, which are regularly distributed around the main axis X1. The number of the permanent magnets 76 and their arrangement define the number of pole pairs p3 of the outer ring 73. In Figure 5 the example shown, the magnets 76 are even in number and define an alternation of positive and negative poles around the axis X1, such that the number of pole pairs p3 is 10.

[0057] The intermediate ring 72, which can be called a "modulator", includes a plurality of separate ferromagnetic parts 75, which are regularly distributed around the main axis X1. "Ferromagnetic" should be understood as meaning that the parts 75 have the ability to be magnetized under the action of an external magnetic field (here provided by the permanent magnets 74 and 76). The intermediate ring 72 includes the number n2 of ferromagnetic parts. In Figure 5 the example, the number of the ferromagnetic parts 75 is 14.

[0058] In Figure 1 the example, in the case where the outer ring 73 is fixed to the stator 1, in particular fixed to the housing 11, here fixed to the wall 17, the outer ring 73 forms the stator ring of the reduction gear 7. The rotational speed of the stator ring is zero.

[0059] In Figure 1 the example, in the case where the intermediate ring 72 is fixed to the fan 5, the intermediate ring 72 forms the drive ring. The rotational speed of the drive ring is equal to the speed w5.

[0060] To obtain the best performance of the reduction gear 7, the reduction gear 7 is configured such that the quantities p1, n2 and p3 advantageously satisfy the following relationship:

[0061] [Formula 1]

[0062] n2 = p1 + p3

[0063] The characteristic quantity k of the reduction gear 7 is defined by the following relationship:

[0064] [Formula 2]

[0065]

[0066] For Figure 1 the case of, the reduction ratio is written as:

[0067] [Formula 3]

[0068]

[0069] For Figure 1 the case of, the quantities n2, p1 and p3 are thus selected such that they adapt to the value of k in order to obtain the desired reduction ratio R.

[0070] For Figure 2 the second embodiment of, all the features of the electric motor are the same as those described above for Figure 1 and are denoted by the same reference numerals. Figure 2 The electric motor of Figure 1 differs from the electric motor of

[0071] in that the intermediate ring 72 is fixed to the stator 1, in particular to the housing 11, here to the wall 17, such that the intermediate ring 72 forms the stator ring, and in that the outer ring 73 is fixed to the fan 5 and thus forms the drive ring.

[0072] [Formula 4]

[0073]

[0074] For Figure 2 the case of, since the relationship between the reduction ratio and the quantity k is changed compared to Figure 1 the quantities n2, p1 and p3 are changed if necessary in order to obtain the desired reduction ratio R, the aim being to obtain a speed w5 that is less than the speed w3.

[0075] Thus, by means of the same reduction gear 7 for which the quantities p1, n2 and p3 are pre-determined, the reduction ratio R can be changed by flipping the rings 72 and 73, that is to say, by choosing which of the rings 72 and 73 is the drive ring or the stator ring respectively.

[0076] For Figure 3 the third embodiment of, all the features of the electric motor are the same as those described above for Figure 1 and are denoted by the same reference numerals. Figure 3 The electric motor of Figure 1The motor is different in that the magnetic deceleration device 7 is axially arranged between the fan 5 and the flange 13. The outer ring 73 of the stator coil is fixed to the stator 1 by means of the flange 13. For example, it is stipulated that the stator coil is fixed to the flange 13 by one or more fixing claws 29. The inner ring 71 abuts against or is near the bearing 37 and is fixed to the end 33 of the shaft on the outside of the fan 5. This arrangement of the magnetic deceleration device 7 enables its maintenance and assembly to be facilitated, but is not conducive to its protection against the outside.

[0077] For Figure 4 the fourth embodiment, all the features of the motor are the same as those described above for Figure 3 , except that the intermediate ring 72 forms the stator coil and is fixed to the stator 1 by means of the flange 13, in particular by the claws 29, and is represented by the same reference numerals. Therefore, the drive ring formed by the outer ring 73 is fixed to the fan 5.

[0078] For Figure 4 the case, since the relationship between the reduction ratio and the quantity k is changed compared to Figure 3 , the quantities n2, p1 and p3 are changed if necessary to obtain the desired reduction ratio R, with the aim of obtaining a speed w5 less than the speed w3.

[0079] As Figures 1 to 4 shown, the present invention is applicable to a closed self-ventilated motor, especially in the case where the ventilation air 23 circulates along the housing 11 containing the stator coil 12 and penetrated by the rotor 3, rather than circulating inside the housing 11. As a variant, the motor is an open motor, in which the circulating air passes through the housing 11, and preferably the fan 5 is arranged inside the housing 11. In this variant, the flange 13 and the skirt 15 are not required.

[0080] As a variant, it is stipulated that the stator includes an armature and the rotor includes induction means, and the armature and the induction means are preferably accommodated inside the housing 11.

[0081] Any feature described above for one of the embodiments or one of the variants can be implemented in the above other embodiments or variants as long as it is technically feasible.

Claims

1. Traction motor of a vehicle, the motor comprises: a stator (1); a rotor (3) which is designed to rotate relative to the stator (1) about the main axis (X1) of the motor at a speed w3 greater than 5000 rpm under the action of the electrical energy fed to the motor; a fan (5) which is designed to rotate relative to the stator (1) about the main axis (X1) at a speed w5 to ventilate the motor; a magnetic reduction gear (7) by means of which the rotor (3) drives the fan (5) to rotate, the magnetic reduction gear (7) being designed to transfer the rotation of the rotor (3) to the fan (5) with a reduction ratio of [Formula 5] R = w5 / w3 wherein: the absolute value of the reduction ratio R is less than or equal to 0.85, the magnetic reduction gear (7) comprises: an inner ring (71) fixed relative to the rotor (3), which includes a plurality of separate permanent magnets (74) distributed around the main axis (X1) and constituting the number of pole pairs p1; an intermediate ring (72), which includes a number n2 of separate ferromagnetic parts (75) distributed around the main axis (X1); and an outer ring (73), which includes a plurality of separate permanent magnets (74) distributed around the main axis (X1) and constituting the number of pole pairs p3; a stator ring selected from the intermediate ring (72) and the outer ring (73) is fixed relative to the stator (1); a drive ring selected from the intermediate ring (72) and the outer ring (73) and different from the stator ring at the same time is fixed relative to the fan (5); the stator (1) comprises: a housing (11) which is penetrated by the rotor (3) along the main axis (X1) and contains induction means (12) and an armature (32) belonging to the motor; and a flange (13) which is attached to the housing (11) and is provided with an air circulation opening (14) penetrated by the main axis (X1); and the fan (5) is arranged along the main axis (X1) outside the housing (11), between the housing (11) and the flange (13), and is configured such that the ventilation air circulates through the air circulation opening (14) to ventilate the motor; the magnetic reduction gear (7) is arranged along the main axis (X1) between the fan (5) and the flange (13); and the stator ring is fixed relative to the stator (1) by being attached to the stator (1) by means of the flange (13).

2. The motor according to claim 1, wherein, the magnetic reduction gear (7) is configured such that the quantities p1, n2 and p3 satisfy the following relationship: [Formula 1] n2 = p1 + p3.

3. The motor according to any one of claims 1 or 2, wherein: the outer ring (73) is a drive ring which is fixed relative to the fan (5); the intermediate ring (72) is a stator ring which is fixed relative to the stator (1); and The reduction ratio is written as [Equation 4] where [Formula 2] 4. The motor according to claim 2, wherein: the outer ring (73) is a stator ring which is fixed relative to the stator (1); the intermediate ring (72) is a drive ring which is fixed relative to the fan (5); and The reduction ratio is written as [Formula 3] where [Formula 2] 5. The motor according to any one of claims 1 or 2, wherein, The rotor (3) includes a rotor shaft (31) coaxial with the main axis (X1), which rotates at a speed w3 when the rotor (3) rotates at a speed w3, and supports the fan (5) by means of a rolling bearing (37), and the fan (5) can rotate relative to the rotor (3) about the main axis (X1).

6. The electric motor according to any one of claims 1 or 2, wherein, the absolute value of the reduction ratio R is equal to 0.

5.

7. A railway vehicle comprising the electric motor according to any one of the preceding claims, the electric motor ensuring the traction of the railway vehicle.

Images