Propulsion system for an electric or hybrid vehicle

Abstract

The invention relates to a drive system (1) for an electric or hybrid vehicle, comprising, in an orthogonal reference frame (XYZ):-a set of n rotating electric machines (2), n being an integer greater than or equal to 2, each machine comprising a stator (21) and a rotor (22) provided with pairs of poles (25) and having an output shaft (23) rotatable about a machine axis (Xn), the n motors comprise pairs of magnetic poles (25) of the same number (P); -a drive shaft (11, 11 ') provided with a gear having an axis of rotation (A) and able to receive the motor torque supplied by the n electric machines (2),-a gearbox (4) carrying the n electric machines, the motor axes (Xn) of the n electric machines (2) being angularly distributed about the axis of rotation (A) of the drive shaft according to a specific position.

Description

Technical Field

[0001] The present invention relates to a propulsion system for an electric or hybrid vehicle. The propulsion system particularly includes a plurality of electric motors for supplying drive torque and at least a series of gear trains for connection to vehicle wheels. Optionally, the propulsion system may include a selective coupling system capable of providing a plurality of reduction ratios and a plurality of independent operating modes for a vehicle user. When the vehicle further includes an internal combustion engine coupled to the electric motor, the vehicle is referred to as a "hybrid" vehicle because it can be propelled either entirely by the electric motor or entirely by the internal combustion engine, or in a hybrid mode using both types of energy simultaneously.

[0002] In the case of a vehicle with pure electric propulsion, in other words, without an internal combustion engine, the electric power can be provided by a battery or a fuel cell with hydrogen as a reducing agent fuel. The electric vehicle can be a motor vehicle or an industrial vehicle, such as a heavy vehicle, a bus, or a tractor. Background Art

[0003] Such a propulsion system is known, for example, from patent application DE102011056048 A1. The propulsion system has a first reversible electric motor and a second reversible electric motor attached to a transmission housing, and a transmission designed to transmit torque from the electric motors to the paired driven wheels of the vehicle, particularly through a common drive shaft. The electric motors are arranged symmetrically with respect to the common drive shaft. Thus, each electric motor includes a pinion designed as a spur gear, which is connected to the output shaft of the rotor for co-rotation. The pinions of the two output shafts assigned to the electric motors mesh with a common spur gear of the transmission, and the rotor output shafts are parallel. The drive torque is transmitted through the common spur gear into the common drive shaft and is transmitted out through bevel gears associated with a differential. In the propulsion system, the rotor output shaft and the common drive shaft are supported by the transmission housing through guide bearings.

[0004] Other applications are known in which there are multiple rotating electric motors meshing with a common gear, such as four electric motors angularly distributed around the common gear. The drive torques output by the four electric motors are added together, and this may lead to an increase in the same excitation sequence of the electric motors within the same cycle. Therefore, there is a risk of a significant increase in the amplitude of the excitation command, which is proportional to the number of in-phase electric motors. This may cause significant bending of the meshing gears in the kinematic gear connection or even damage the guide bearings supporting the common gear.

[0005] There is a need to improve the acoustic comfort of a propulsion system for an electric or hybrid vehicle, which includes a plurality of electric motors and a series of gear trains attached to a transmission housing. There is also a need to improve the mechanical reliability of such a propulsion system. Summary of the Invention

[0006] The present invention particularly proposes to improve such a known propulsion system.

[0007] To this end, the subject of the present invention is a propulsion system for an electric or hybrid vehicle, which in an orthogonal reference system XYZ comprises:

[0008] - A set of n rotary electric machines, where n is an integer greater than or equal to 2, each machine comprising a stator and a rotor, the rotor being equipped with pairs of magnetic poles and having an output shaft rotatable about the axis of the machine, and the n machines comprising the same number P of pairs of magnetic poles;

[0009] - A drive shaft, which is equipped with at least one gear on the axis of rotation of the drive shaft and is capable of receiving the drive torque provided by the n machines and is kinematically connected to the n output shafts;

[0010] - A transmission housing, which supports the n machines and at least partially supports the drive shaft;

[0011] Wherein, the axes of the n machines are angularly distributed around the axis of rotation of the drive shaft, and the angular orientation of the stator of one of the machines is offset by an angular value β along its own axis of the machine with respect to the angular orientation of the stator of another machine, such that: β = 360° / [P×n].

[0012] The advantage of such a propulsion system is that the magnetic poles are offset due to the angular offset of the machines during the assembly of the machines onto the transmission housing. In this way, the period of each machine is offset, and the maximum amplitude of the excitation command of the machines is reduced with respect to the drive shaft. Therefore, the acoustic comfort and mechanical reliability of the propulsion system are improved.

[0013] For example, the rotor may comprise a number P of pole pairs between 2 and 12, for example between 4 and 8. In this way, the amplitude of the excitation command of the machines is reduced compared to the disadvantageous case of amplitude addition. This limits the bending of the gears and pinions forming different gear trains and avoids damaging the guide bearings supporting the drive shaft.

[0014] Therefore, the drive shaft rotates about the axis of rotation of the drive shaft and comprises at least a gear, which is capable of receiving the drive torque provided by the n machines and is kinematically connected to the n output shafts without generating operating noise within the propulsion system.

[0015] Advantageously, the axes of rotation of the rotors of the n machines and the axis of rotation of the drive shaft are parallel to each other.

[0016] Preferably, the drive shaft rotating about the axis of rotation of the drive shaft can be directly meshed with the n rotor output shafts through at least one gear. For example, the direct meshing of the drive shaft can be achieved through a common gear in direct contact with the n rotor output shafts or through a plurality of independent gears in direct contact with the associated rotor output shafts.

[0017] According to an embodiment of the present invention, the integer n of the electric motors can be greater than 2, and each stator of the set of electric motors can be offset by an angular value β along its own motor axis with respect to the angular orientation of the stator of the adjacent electric motor. In this way, the acoustic comfort and mechanical reliability of the propulsion system are improved.

[0018] Advantageously, the transmission housing and each electric motor can include angular positioning means for positioning each electric motor individually with respect to the transmission housing.

[0019] Preferably, the angular positioning means can be constituted by protruding positioning devices distributed respectively on the transmission housing or the electric motor and recessed receiving devices associated with the protruding positioning devices, the recessed receiving devices being distributed respectively on the electric motor or the transmission housing. This makes it easier to assemble the propulsion system.

[0020] Advantageously, each electric motor can include a protective cover supporting the stator and fastening mounts adapted to the transmission housing, the fastening mounts including through-holes for fastening screws and partly including angular positioning means.

[0021] Preferably, the protective cover of the electric motor can include a protruding positioning device formed as an integral part of the fastening mount or attached to the fastening mount.

[0022] According to a variant of the present invention, the protruding positioning device can be an axial protrusion along an axis parallel to the motor axis, and the recessed receiving device can be a cylindrical orifice matching the shape of the protrusion, the axial protrusion being, for example, a pin.

[0023] Advantageously, the protruding positioning device or the recessed receiving device can be directly incorporated into the stator of the electric motor.

[0024] Advantageously, each rotor output shaft can include a pinion, and the angular meshing position of the pinion of one electric motor with at least one gear of the drive shaft is angularly offset with respect to the angular meshing position of the pinion of at least one other electric motor with the same gear or another gear of the drive shaft.

[0025] Preferably, the angular offset of the meshing of the pinion with the drive shaft can correspond to 1 / n teeth of the pinion. This makes the torque transmission within the gear train uniform.

[0026] Each electric motor is, for example, a rotary electric motor. The electric motor can in particular be a variable reluctance motor that is synchronous or asynchronous (with or without magnets). Alternatively, the n electric motors can have different designs.

[0027] As a variant, the n electric motors can preferably be high-voltage electric motors, for example powered at a rated voltage between 300 volts and 800 volts. Higher supply voltages can be envisaged, for example 1000 volts. As a variant, the n electric motors can be powered at 48 volts.

[0028] n electric motors can provide the same mechanical rated power, which is, for example, between 50 kW and 300 kW. By reducing the need for specific development from one motor to another and by increasing the volume, using the same motors can reduce the production cost of the propulsion system.

[0029] Each motor can be configured to operate reversibly, in which case it is associated with electronic devices such as inverters / rectifiers, allowing it to be alternately supplied with electrical energy to provide driving torque and, for example, when the vehicle brakes or coasts, to generate electrical energy based on the torque received by its output shaft.

[0030] Preferably, the rotor of one motor can be axially arranged on one side of at least one gear of the drive shaft, while the rotor of the other motor can be arranged on the other side of at least one gear.

[0031] Advantageously, the transmission housing can have an outer wall, at least one planar support surface provided on the outer wall, the support surface defining a plane perpendicular to the axis of the guide bearing for supporting n electric motors, and n openings formed in one or more planar support surfaces, each of the n openings having an output shaft of the motor rotor passing through it.

[0032] According to a preferred embodiment of the present invention, the drive shaft can include a common gear kinematically connected to the output shafts of each rotor, and the n electric motors are angularly distributed around the common gear so as to form a reduction gear between each rotor output shaft and the common gear.

[0033] According to another preferred embodiment of the present invention, the drive shaft can include two independent gears, and the output shafts of each rotor are distributed on the two gears, thereby forming two independent reduction gears between each rotor output shaft and the associated gear.

[0034] The present invention can be applied to synchronous motors with permanent magnet rotors, and preferably to permanent magnet synchronous reluctance motors or motors with flux-concentrated rotors.

[0035] Advantageously, the stator of the motor supplied with polyphase current can have a magnetic circuit including teeth, and the teeth form slots for receiving electrical conductors between each other.

[0036] Preferably, the stator can include a three-phase winding connected in a substantially star configuration, divided into pairs of poles, and the winding is inserted into the slots formed in the stator.

[0037] Advantageously, the stator can include winding positioning slots associated with the pairs of poles of the motor, and the angular positioning means are angularly indexed with respect to the slots.

[0038] Preferably, the rotating electrical machine may have a permanent magnet rotor. The pair of poles may include permanent magnets received in recesses provided in the magnetic body of the rotor and arranged to form a plurality of alternating north and south poles. The pair of poles may include so-called salient poles which include coils wound around the radial arms of the rotor. In this case, the poles are formed by the coils. The number of poles P provided in the rotor in this way may vary according to the application of the rotating electrical machine, and the number of slots formed in the stator may also vary, and windings are provided in these slots.

[0039] Each pole of the rotor may have at least one magnet, such as a single magnet per pole, or as a variant, two magnets per pole, or even more magnets. The permanent magnet may have a rectangular overall shape.

[0040] The magnetic body of the rotor may be formed by a stack of laminations or one or more individual laminations wound around itself about the axis of rotation. Each lamination of the magnetic body of the rotor may be formed as a single piece.

[0041] According to another aspect of the present invention, the present invention may include a propulsion system for an electric vehicle, comprising:

[0042] - A set of n propulsion motors, where n is an integer greater than or equal to 2, each motor including a stator and a rotor having an output shaft rotatable about an axis;

[0043] - A common gear kinematically connected to the n output shafts and capable of receiving the drive torque provided by the n motors, the n motors being angularly distributed about the common gear so as to form a first reduction gear,

[0044] The propulsion system includes:

[0045] - A main gear capable of being driven by the common gear;

[0046] - An intermediate shaft capable of being driven by an intermediate gear, each main gear being kinematically connected to a corresponding intermediate gear, thereby forming a pair of gears, and a second reduction gear is associated with the pair of gears;

[0047] - A second shaft capable of driving a set of one or more drive wheels of the vehicle and having a second gear kinematically connected to the intermediate shaft, thereby forming a third reduction gear;

[0048] Wherein, a first selective coupling system provided between the common gear and the main gear or alternatively provided between the intermediate shaft and the intermediate gear selects a first pair of gears or a second pair of gears from a neutral position.

[0049] Axially, the angular distribution of the n motors about the common gear allows the propulsion system to be installed with a smaller space requirement. Description of the Drawings

[0050] With reference to the accompanying drawings, other features and advantages of the present invention will become apparent from the following description.

[0051] Figure 1 is a perspective view of a propulsion system for an electric or hybrid vehicle according to a first exemplary embodiment of the present invention,

[0052] Figure 2 is according to Figure 1 a front view of the propulsion system according to the first exemplary embodiment of the present invention in

[0053] Figure 3 is a detailed view of the electric machine of the propulsion system according to the first exemplary embodiment of the present invention,

[0054] Figure 4 is a perspective view of a propulsion system for an electric or hybrid vehicle according to a second exemplary embodiment of the present invention,

[0055] Figure 5a is according to Figure 4 a detailed view of the propulsion system according to the second exemplary embodiment of the present invention in

[0056] Figure 5b is according to Figure 4 another detailed view of the propulsion system according to the second exemplary embodiment of the present invention in

[0057] For greater clarity, in all the figures, the same or similar elements are identified by the same reference numerals. DETAILED DESCRIPTION

[0058] Figure 1 、 2 and 3 show an electric vehicle propulsion system 1 according to a first exemplary embodiment of the present invention, including a set of four rotating electric machines 2 in an orthogonal reference coordinate system XYZ, each of the reversible electric machines 2a, 2b, 2c and 2d being kinematically connected to a common drive shaft 11. In this case, the propulsion system 1 is purely electric, which means that it does not use an internal combustion engine to drive the vehicle, and in this case, the vehicle is an industrial vehicle, such as a heavy goods vehicle.

[0059] In the orthogonal reference system XYZ, the planes XY, YZ and XZ are perpendicular to each other.

[0060] The rotating electric machines 2a, 2b, 2c, 2d are of the same type and are, for example, permanent magnet synchronous electric machines. Each electric machine supplies the same mechanical rated power, which is, for example, about 100 kW. As a variant, for example, they can be asynchronous electric machines.

[0061] Each motor includes a stator 21 and a rotor 22. The rotor 22 is equipped with pairs of magnetic poles 25 and has an output shaft 23 that can rotate about the axis of the motor. The four motors include the same number P of pairs of magnetic poles. In this example, the number of pairs of poles is P = 4.

[0062] In this propulsion system 1, each of the motors 2a, 2b, 2c, and 2d includes a stator 21 radially arranged outside the rotor 22 and a protective cover 24 surrounding the stator. The motors are attached to the transmission housing 4, which has an outer wall 41 and a planar support surface 42 that defines a plane YZ perpendicular to the axis X of the orthogonal reference system and is provided on the outer wall 41 to support the four motors. The transmission housing 4 defines an internal space 40, and the gear train 3 is arranged in the internal space 40.

[0063] The protective cover 24 of the motor includes a fastening mount 26 for fastening to the planar support surface 42 of the transmission housing 4. An opening 43 is formed in the planar support surface 42 along an axis parallel to the axis X, allowing the rotor 22 to enter the internal space 40. Each opening 43 has the output shaft 23 of the motor rotor 22 passing through it.

[0064] As Figure 2 shown, in the described example, the first motor 2a has a rotor 22 with a first output shaft 23 that rotates about a first rotation axis X1, the second motor 2b has a rotor 22 with a second output shaft 23 that rotates about a second rotation axis X2, the third motor 2c has a rotor with a third output shaft that rotates about a third rotation axis X3, and the fourth motor 2d has a rotor with a fourth output shaft that rotates about a fourth rotation axis X4. In the described example, the rotation axes of the rotating motors are parallel but not coincident, and the rotation axes of the four motors 2a, 2b, 2c, and 2d are not aligned. The rotation axes of the four motors are regularly distributed around the rotation axis A of the drive shaft 11 at an angle equal to 90°.

[0065] Each rotor output shaft 23 includes a pinion Z1 coupled to a gear Z2 of the drive shaft 11. The gear Z2 is in the form of a common gear Z2 so as to form a reduction gear Z1, Z2 between each rotor output shaft and the common gear. The output shafts 23 of the four motors are simultaneously engaged with the common gear Z2 provided within the axes X1, X2, X3, and X4. The common gear Z2 thus receives the driving torque C0 provided by the four motors.

[0066] The propulsion system 1 includes main gears Z3, Z5, which can be driven by a common gear Z2 via a selective coupling system 10. A first selective coupling system 10 provided between the common gear Z2 and the main gears Z3, Z5 enables the selection of a first pair of gears Z3, Z4 or a second pair of gears Z5, Z6 from an uncoupled neutral position. This three-position selective coupling system 10 takes the form of a claw clutch. As a variant, the coupling system can include two coupling sub-assemblies, the first only associated with the first pair of gears Z3, Z4 and the second only associated with the second pair of gears Z5, Z6. As a variant, the coupling system can take the form of a synchronizer.

[0067] The propulsion system 1 includes an intermediate shaft 12 that can be driven by intermediate gears Z4, Z6 and Z7. Each main gear Z3, Z5 is kinematically connected to a corresponding intermediate gear Z4, Z6 to form a pair of gears, and a second reduction gear is associated with this pair of gears. The intermediate shaft 12 is rotationally supported by the transmission housing 4 with the help of a guide bearing 50.

[0068] The propulsion system 1 further includes a second shaft 13 that can drive a set of one or more drive wheels of the vehicle. The second shaft 13 has a second gear Z8, which is kinematically connected to the intermediate shaft 12 via an intermediate gear Z7 to form a third reduction gear Z7, Z8.

[0069] In this first embodiment of the invention, the rotational axis A of the common gear Z2, the rotational axis of the intermediate shaft 12, and the rotational axis of the second shaft 13 are parallel.

[0070] Depending on the configuration of the first selective coupling system 10 for selecting the first pair of gears Z3, Z4 or the second pair of gears Z5, Z6, the second shaft 13 receives different torque values. Based on the driving torque C0 transmitted by four motors, it selectively receives: the torque C1 that has been transmitted through the first pair of gears, or the torque C2 that has been transmitted through the second pair of gears, such that C1 > C2.

[0071] Advantageously, a first ratio between the driving torque C0 and the torque C1 that has been transmitted through the first pair of gears Z3, Z4 can be between 10 and 15, such that 10 < C0 / C1 < 15, and a second ratio between the driving torque C0 and the torque C2 that has been transmitted through the second pair of gears Z5, Z6 can be between 5 and 10, such that 5 < C0 / C2 < 10.

[0072] As an indication, in the case of an industrial vehicle, the first ratio can be equal to 10.5 and the second ratio can be equal to 6.

[0073] The transmission housing 4 supports four electric motors and the common gear Z2 by means of a guide bearing. Due to the geometric distribution of the electric motors around the common gear, the transmission housing supports more evenly distributed mechanical stresses. The transmission housing generally consists of a plurality of housings connected together, thereby forming a closed housing body that protects the gear train 3.

[0074] To improve the acoustic comfort of the propulsion system, the present invention provides that the motor axes X1, X2, X3, X4 are angularly distributed around the rotational axis A of the drive shaft, and the angular orientation of the stator of one of the motors is offset by an angular value β along its own motor axis relative to the angular orientation of the stator of another motor, such that: β = 360° / [P×n], where P is the number of pairs of poles 25 and n is the number of motors. In this example, P = 4 and n = 4, so the angle β = 360° / [4×4] = 22.5°.

[0075] More specifically, the angular orientation of each stator 21 of the set of electric motors is offset by an angular value β = 22.5° along its own motor axis relative to the angular orientation of the stator 21 of the adjacent motor.

[0076] The advantage of such a propulsion system is that the magnetic poles are offset due to the angular offset during the assembly of the electric motors on the transmission housing 4. In this way, the period of each electric motor is offset and the maximum amplitude of the excitation command of the electric motor is reduced. Therefore, the acoustic comfort and mechanical reliability of the propulsion system are improved.

[0077] As Figure 1 and 3 shown, the transmission housing 4 and each electric motor 2 include angular positioning means 55 for positioning each electric motor individually relative to the transmission housing. The angular positioning means 55 consists of protruding positioning devices 56 distributed on the electric motor and recessed receiving devices 57 associated with the protruding positioning devices 56. The recessed receiving devices 57, which consist of a series of orifices, are distributed on the transmission housing 4. This makes it easier to assemble the propulsion system.

[0078] Each electric motor 2 includes a protective cover 24 that supports the stator 21 and fastening mounts 26 adapted to the transmission housing 4. The fastening mounts 26 include through holes 27 for fastening screws and partly include the angular positioning means 55.

[0079] Figure 3 A permanent magnet type electric motor 2 is shown, which includes a stator 21 (also called an armature) and a flux concentrating rotor 22 with a rotating magnet, and a housing 29 is provided to define the poles of the rotor. Each pole has a radial axis Y. In this example, each pole of the rotor 22 has three housings 29, which are concentrated around each pole, and the concave surfaces of the housings are oriented towards the air gap of the rotating electric motor.

[0080] In the present case, the rotor has twenty-four permanent magnets 30. Each magnet 30 is in the form of a block, has a substantially rectangular cross-section, and each magnet is arranged radially with respect to the center of the rotor in order to obtain a rotor structure of the flux concentration type. In addition, the magnets are arranged to have radially alternating north magnetic poles 25 and south magnetic poles 25 on the same axial plane of the rotor, thereby forming four pairs of consecutive alternating north and south poles. As Figure 3 shown, the magnets can be advantageously radially segmented, for example into two, three or four parts. The case shown in the figure corresponds to a radial segmentation into three parts.

[0081] The stator 21 of the electric machine supplied with polyphase current includes a magnetic circuit, which includes teeth 32 that form radially arranged slots 31 therebetween for receiving electric conductors. The conductors of the armature are positioned in the slots 31 angularly distributed around the frame of the electric machine and are grouped into coils. For example, the winding of the stator is a source of single-phase or three-phase alternating current. The slots 31 have an appropriate depth such that the coils they accommodate are completely received in the stator and do not impede the rotation of the rotor in the stator. The regular distribution of the slots 31 forms a plurality of teeth 32, each tooth extending between two adjacent slots.

[0082] In this first exemplary embodiment of the invention, the protective cover 24 of the electric machine includes a protruding positioning device 56, which is attached to the fastening mount 26. The protruding positioning device 56 is an axial projection along an axis parallel to the axis X of the electric machine, for example a pin. The axis of the pin 56 is angularly indexed with respect to the slots 31 at an angle α. This angle α depends on the position of the coils and thus on the polarity of the stator 21. In this way, the angular positioning device 55 is angularly indexed with respect to the said slots 31.

[0083] In a complementary manner, the recessed receiving device 57 is a cylindrical orifice that matches the diameter of the pin 56. Thus, the angular positioning device 55 consists of four pins 56 distributed on the electric machines 2a, 2b, 2c, 2d and four cylindrical orifices 57 machined into the transmission housing 4.

[0084] According to a variant of the invention, the angular positioning device 55 can consist of teeth 56 distributed on the electric machines 2a, 2b, 2c, 2d and four recesses 57 directly molded into the transmission housing 4. The shape of the recesses 57 then matches the shape of the teeth 56.

[0085] According to another variant of the invention, the angular positioning device 55 can consist of a protruding positioning device 56 (for example a pin inserted into the transmission housing) distributed on the transmission housing and a recessed receiving device 57 associated with the protruding positioning device, the recessed receiving device 57 being distributed on the electric machines, for example recesses directly formed in the stator of each electric machine. The transmission housing 4 generally includes a plurality of housings connected together, thereby forming a closed housing body for protecting the propulsion system 1.

[0086] Reference will now be made to Figure 4 、 5a and 5b to describe the propulsion system 1 including only two motors according to the second embodiment of the present invention. The difference of this second embodiment of the present invention is that the motors are meshed with the same drive shaft through two independent gears. The rotating motors 2a, 2b are of the same type and are, for example, synchronous motors.

[0087] In this propulsion system 1, each motor 2a, 2b includes a stator 21 radially arranged outside the rotor 22 and a protective cover 24 surrounding the stator. The first motor 2a has a first rotation axis X1, and the second motor 2b has a second rotation axis X2. The rotation axes of the rotating motors are parallel but not coincident, and the rotation axes of the two motors are not aligned.

[0088] As Figure 4 shown, the protective cover 24 of the motor 2a is attached to the transmission housing 4. The other protective cover 24 of the motor 2b is similarly attached to the transmission housing 4. The transmission housing 4 supports the motors 2a, 2b and the drive shaft 11 by means of a guide bearing 50 inserted into a cylindrical housing 45 provided on the wall of the transmission housing 4. In this case, the guide bearing 50 is a ball bearing, and the non-rotating ring on its outside is inserted into the cylindrical housing 45 of the transmission housing.

[0089] In this second embodiment, the rotor 22 of the motor 2a has an output shaft 23 kinematically connected to the drive shaft 11, which can rotate about the motor axis X1. The rotor 22 of the motor 2b has an output shaft 23 kinematically connected to the drive shaft 11, which can rotate about the motor axis X2. The drive shaft 11 with the rotation axis A includes two independent torque input gears Z2, Z3 and a torque output gear Z4. The output shaft 23 of each rotor is distributed on the two gears Z2, Z3, thereby forming two independent reduction gears Z1, Z2 and Z1', Z3 between each rotor output shaft and the associated gear.

[0090] In the propulsion system 1 according to the present invention, the axes X1, X2 of the two motors 2a, 2b are angularly distributed around the rotation axis A of the drive shaft 11. To improve the acoustic comfort of the propulsion system, the angular orientation of the stator of the motor 2a is offset by an angular value β along its own motor axis relative to the angular orientation of the stator of the other motor 2b, such that: β = 360° / [P×n], where P is the number of pairs of poles 25 and n is the number of motors. In this example, P = 4, n = 2, so the angle β = 360° / [4×2] = 45°.

[0091] In a second exemplary embodiment of the present invention, the protective cover 24 of the electric machine includes a protruding positioning device 56. The protruding positioning device 56 is an axial protrusion along an axis parallel to the axis X of the electric machine, such as a pin. In a complementary manner, the recessed receiving device 57 is a cylindrical orifice that matches the diameter of the pin 56 and is provided in the transmission housing 4. Thus, the angular positioning device 55 consists of two pins 56 distributed on the electric machines 2a, 2b and two cylindrical orifices 57 machined into the transmission housing 4.

[0092] The second embodiment of the present invention also differs from the first embodiment in that the propulsion system includes two electric machines, and each rotor output shaft 23 includes pinions Z1, Z1'. The angular engagement position of the pinion Z1 of one of the electric machines 2a with the gear of the drive shaft 11 is angularly offset with respect to the angular engagement position of the pinion Z1' of at least one other electric machine 2b.

[0093] When the propulsion system 1 includes two identical electric machines as shown in Figure 5a and 5b the angular offset of the engagement of the pinions Z1 and Z1' with the drive shaft 11 including the common gear Z2 corresponds to 1 / 2 tooth of the pinion Z1. Thus, the rotor output shaft 23 of the electric machine 2a engages with the common gear Z2 and has an angular offset of half a tooth with respect to the rotor output shaft 23 of the electric machine 2b. This makes the torque transmission within the gear train uniform.

[0094] The present invention is not limited to the examples just described. In another exemplary embodiment of the present invention, the propulsion system 1 may be equipped with a plurality of reversible electric machines coupled to the transmission of a hybrid vehicle, which also includes an internal combustion engine, a gearbox, and a friction clutch mechanism provided between the engine and the gearbox.

Claims

1. A propulsion system (1) for an electric or hybrid vehicle, comprising in an orthogonal reference system (XYZ): - A set of n rotating electric machines (2), where n is an integer greater than or equal to 2. Each electric machine includes a stator (21) and a rotor (22). The rotor is equipped with pairs of magnetic poles (25) and has an output shaft (23) capable of rotating about the axis (Xn) of the electric machine. The n electric machines include the same number (P) of pairs of magnetic poles (25); - Drive shafts (11, 11'), which are equipped with at least one gear (Z2, Z3) having the axis of rotation (A) of the drive shaft, and are capable of receiving the driving torque provided by the n electric machines (2) and are kinematically connected to the n output shafts (23); - A transmission housing (4), which supports the n electric machines (2) and at least partially supports the drive shafts (11, 11'); Wherein, the axes (Xn) of the n electric machines (2) are angularly distributed around the axis of rotation (A) of the drive shaft, and the angular orientation of the stator (21) of one of the electric machines (2) is offset by an angular value β along its own axis (Xn) of the electric machine with respect to the angular orientation of the stator of another electric machine, such that: β = 360° / [P×n].

2. The propulsion system (1) according to claim 1, wherein, The integer n of the electric machines is greater than 2, and the angular orientation of the stator (21) of each electric machine in the set of electric machines (2) is offset by the angular value β along its own axis (Xn) of the electric machine with respect to the stator of the adjacent electric machine.

3. The propulsion system (1) according to any one of the preceding claims, wherein, The transmission housing (4) and each electric machine include angular positioning means (55) for positioning each electric machine (2) individually with respect to the transmission housing (4).

4. The propulsion system (1) according to claim 3, wherein, The angular positioning means (55) consists of protruding positioning devices (56) respectively distributed on the transmission housing or the electric machine and recessed receiving devices (57) associated with the protruding positioning devices. The recessed receiving devices (57) are respectively distributed on the electric machine or the transmission housing.

5. The propulsion system (1) according to any one of the preceding claims, wherein, Each electric machine (2) includes a protective cover (24) supporting the stator and fastening mounting means (26) adapted to the transmission housing. The fastening mounting means (26) includes through holes for fastening screws and partially includes the angular positioning means (55).

6. The propulsion system (1) according to claim 5, wherein, The protective cover (24) of the electric machine includes the protruding positioning device (56), which is formed as an integral part of the fastening mounting means (26) or attached to the fastening mounting means.

7. The propulsion system (1) according to any one of claims 4 to 6, wherein, The protruding positioning device (56) is an axial protrusion along an axis parallel to the axis (Xn) of the electric machine, and the recessed receiving device (57) is a cylindrical orifice matching the shape of the protrusion. The axial protrusion is, for example, a pin.

8. The propulsion system (1) according to claim 4, wherein, The protruding positioning device (56) or the recessed receiving device (57) is directly incorporated into the stator (21) of the electric machine.

9. The propulsion system (1) according to any one of the preceding claims, wherein, Each rotor output shaft (23) includes pinions (Z1, Z1'), and the angular meshing position of the pinions (Z1, Z1') of one of the motors (2) with at least one gear of the drive shaft is angularly offset with respect to the angular meshing position of the pinions of at least one other motor with the same gear or another gear of the drive shaft (11, 11').

10. The propulsion system (1) according to claim 9, wherein, The angular offset of the meshing of the pinions (Z1, Z1') with the drive shaft (11, 11') corresponds to 1 / n teeth of the pinion.

11. The propulsion system (1) according to any one of the preceding claims, wherein, The rotor (22) of one of the motors is axially disposed on one side of at least one gear (Z2, Z3) of the drive shaft, and at least one rotor of the other motor is disposed on the other side of at least one gear (Z2, Z3).

12. The propulsion system (1) according to any one of the preceding claims, wherein, The motor axes (Xn) of the n motors (2) and the rotational axis (A, A1, A2) of the drive shaft are parallel to each other.

13. The propulsion system (1) according to any one of the preceding claims, wherein, The transmission housing (4) has an outer wall (41), at least one planar support surface (42) provided on the outer wall, the support surface (42) defining a plane (YZ) perpendicular to the axis of the guide bearings (50, 50') for supporting the n motors, and n openings (43) formed in one or more planar support surfaces (42), each of the n openings (43) having an output shaft (23) of the motor rotor passing therethrough.

14. The propulsion system (1) according to any one of claims 1 to 13, wherein, The drive shaft includes a common gear (11, 11') kinematically connected to the output shaft (23) of each rotor, and the n motors (2) are angularly distributed around the common gear so as to form reduction gears (Z1, Z2) between each rotor output shaft and the common gear.

15. The propulsion system (1) according to any one of claims 1 to 13, wherein, The drive shaft (11, 11') includes two independent gears (Z2, Z3), and the output shaft (23) of each rotor is distributed on the two gears (Z2, Z3), thereby forming two independent reduction gears (Z1, Z2 and Z1, Z3) between each rotor output shaft and the associated gear.

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