Mechanical drive device for a transmission shaft comprising two rotating machines

Abstract

The present invention relates to a drive device (2) comprising: a frame (4); a first machine (6) comprising a fixed part (8) and a rotating moving part (10); a second machine (12) comprising a fixed part (14) and a rotating moving part (16) configured to transmit a second torque; an epicyclic gear train (18) comprising a ring gear (20), a planet gear (22), and a planet carrier (24) rotating relative to the ring gear (20), the rotating part (10) of the first machine being fixed to the planet carrier (24); a drive shaft (26); a differential (28) configured to transmit a resulting torque to the drive shaft (26); the drive device (2) being characterized in that the moving part (16) of the second machine (12) transmits the second torque to the differential (28). Abstract figure: Figure 1

Description

Title of the invention: Mechanical drive device for a transmission shaft comprising two rotating machines Technical field

[0001] The present invention relates to the technical field of electric vehicles.

[0002] More particularly, the invention relates to the technical field of wheel drive devices for such electric vehicles. STATE OF THE ART

[0003] Known from the state of the art is a vehicle comprising a drive device in which a first rotating machine is configured to rotate a transmission shaft secured to the wheels of said vehicle. When it is desired to allow the wheels of the vehicle to rotate at different speeds, it is also known to insert a differential between the rotating machine and the wheels, in particular when the vehicle passes a curve.

[0004] To increase the mechanical torque received by the wheels of the vehicle, for example to overcome an obstacle such as a slope, it is known to insert between the rotating machine and the transmission shaft, a plurality of gears, making it possible to multiply the mechanical torque generated by said rotating machine. Such gears can for example be arranged within an epicyclic gear train allowing an increase in the rotational speed of the electric machine as well as an increased torque at the wheels by increasing the ratio between the speed of the wheels and the speed of the machine, while offering high compactness. However, in certain applications, the use of an epicyclic gear train does not allow the wheels to receive an acceptable mechanical torque. To increase the resulting mechanical torque, it is then necessary to replace the rotating machine with a more powerful rotating machine.

[0005] The invention aims to overcome all or part of the drawbacks of the state of the art by proposing a drive device making it possible to generate a higher resulting torque and also having a more compact and more reliable architecture. PRESENTATION OF THE INVENTION

[0006] More specifically, the invention relates to a device for mechanically driving a shaft comprising: • a frame; • a first rotating machine comprising a fixed part secured to the frame and a rotating mobile part configured to transmit a first mechanical torque; • a second rotating machine comprising a fixed part secured to the frame and a rotating movable part configured to transmit a second mechanical torque; • a first epicyclic gear train comprising a first crown secured to the frame, a planetary gear movable in rotation relative to the crown and a planet carrier movable in rotation relative to the crown, the movable part of the first rotating machine being secured in rotation to the planet carrier of the epicyclic gear train; • a transmission shaft configured to transmit a resulting torque, • a differential arranged between the first epicyclic gear set and the transmission shaft in the direction of torque transmission, comprising a second crown gear integral in rotation with the sun gear of the first epicyclic gear set, the differential being configured to transmit a resulting torque to the transmission shaft,

[0007] The drive device is remarkable in that the moving part of the second rotating machine transmits the second torque to the differential.

[0008] For the purposes of the application, the fixed part comprises at least one stator. The moving part comprises at least one rotor. The first machine and the second machine may be identical. The first machine or the second machine may be different.

[0009] Thanks to such a combination of characteristics, the drive device allows the rotational driving of a single transmission shaft using two rotating machines rotating in the same direction. In such a configuration, the reliability of such a drive device is significantly increased, the transmission shaft being able to be driven despite possible damage to one of the two rotating machines.

[0010] Advantageously, the first crown is arranged between the fixed part of the first machine and the fixed part of the second machine. In such a configuration, each rotating machine is positioned axially on a given side of the differential and the first epicyclic gear train to transmit the first and second torque to the differential.

[0011] Advantageously, the moving part of the second rotating machine is integral in rotation with the transmission shaft. In such a configuration, the resulting torque transmitted to the transmission shaft is the sum of the first mechanical torque generated by the first rotating machine and the second mechanical torque generated by the second rotating machine. Thus, it is possible to obtain a higher resulting mechanical torque, in particular by controlling the two rotating machines so that each operates at an operating point maximizing its efficiency. The term "operating point" means the configuration of an electrical machine at a given rotational speed for a given mechanical torque.

[0012] Advantageously, the drive device comprises a reducer connecting the moving part of the second rotating machine to the transmission shaft.

[0013] Advantageously, the moving part of the second rotating machine is integral in rotation with the planet carrier of the first epicyclic gear train. In such a configuration, the rotation speed of the two moving parts is identical. The resulting torque transmitted to the shaft is the sum of the mechanical torques of the first machine and of the second machine to the shaft. The torque of each machine may be different, in particular if the structure and / or if the control are different between the two electrical machines. In addition, the distribution of the mechanical torque on the transmission shaft is carried out at different application points, promoting the service life of the transmission shaft.

[0014] Advantageously, the moving part of the first rotating machine and the moving part of the second rotating machine are coaxial.

[0015] Advantageously, the differential is radially arranged inside the first epicyclic gear train. In such a configuration, the compactness of the drive device is improved.

[0016] Advantageously, the first rotating machine is an axial flux electric motor. Preferably, the first machine rotates at a speed greater than 20,000 revolutions / minute.

[0017] Advantageously, the second rotating machine is an axial flux electric motor or a wheel motor.

[0018] Advantageously, when the first machine and / or the second machine are axial flux machines, the fixed part comprises two stators which frame a rotor. Several rotors may be provided, each being framed by two stators. The stators may be fixed to each other and completely encapsulate the rotor. The rotor may comprise permanent magnets which do not require any external excitation. Bearings may be arranged between the stators and the transmission shaft or between the stators and the planet carrier.

[0019] According to another aspect of the invention, it relates to a mobility device comprising a drive device according to any one of the claims. The mobility device is for example an electric vehicle thus comprising two electric motors driving a transmission shaft. PRESENTATION OF FIGURES

[0020] The invention will be better understood on reading the following description, given solely by way of example, and referring to the appended drawings given by way of non-limiting examples, in which identical references are given to similar objects and in which:

[0021] [Fig.l] is a schematic representation of a sectional view of a training device according to a first embodiment of the invention;

[0022] [Fig. 2] is a schematic representation of a sectional view of a training device according to a second embodiment of the invention;

[0023] [Fig. 3] is a schematic representation of a sectional view of a drive device according to a variant of the embodiment of [Fig. 1];

[0024] [Fig.4] is a schematic representation of a sectional view of a drive device according to a variant of the embodiment of [Fig.2];

[0025] It should be noted that the figures set out the invention in detail to enable the invention to be implemented; although not limiting, said figures serve in particular to better define the invention where appropriate. DETAILED DESCRIPTION OF THE INVENTION

[0026] The invention relates in particular to a drive device 2 for an electric vehicle, as illustrated in [Fig.l] according to a first embodiment. The drive device 2 comprises a frame 4. The frame 4 is an element fixed relative to the structure of the electric vehicle, for example secured to a chassis of said vehicle. Here, the drive device 2 is configured to drive wheels 3 of the electric vehicle in rotation, by means of a resulting torque transmitted by a transmission shaft 26 of the drive device 2. In the case of an electric vehicle comprising four wheels 3, the drive device 2 is arranged indifferently between two wheels 3 forming a front axle of the vehicle or a rear axle of the vehicle.

[0027] The drive device 2 comprises a first rotating machine 6 comprising a fixed part 8 secured to the frame 4 and a mobile part 10, mobile in rotation and configured to transmit a first mechanical torque, said first torque being generated by the first rotating machine 6. Preferably, the first rotating machine 6 is an electric motor, more preferably an axial flux electric motor.

[0028] The drive device 2 comprises a second rotating machine 12 comprising a fixed part 14 secured to the frame 4 and a movable part 16, movable in rotation and configured to transmit a second mechanical torque, said second torque being generated by the second rotating machine 12. Preferably, the second rotating machine 12 is an electric motor, more preferably an axial flux electric motor. Alternatively, the second rotating machine 12 is a wheel motor.

[0029] The drive device 2 also comprises a first epicyclic gear train 18. The first epicyclic gear train 18 comprises a crown 20, secured to the frame 4, a planetary 22 movable in rotation relative to the crown 20 and a planet carrier 24 movable in rotation relative to the crown 20. In particular, the planetary 22 and the planet carrier 24 are coaxial and mechanically connected, of the gear type, by means of satellites.

[0030] The planet carrier 24 is rotationally secured to the mobile part 10 of the first rotating machine 8, so that the mobile part 10 transmits the first mechanical torque to the planet carrier 24.

[0031] The drive device 2 further comprises a differential 28. The differential 28 is arranged between the first epicyclic gear set 18 and the transmission shaft 26 in the direction of torque transmission. The differential 28 comprises a crown, integral in rotation with the sun gear 22 of the first epicyclic gear set. Furthermore, the moving part 16 of the second rotating machine 12 transmits the second torque to the differential 28. In other words, the differential 28 is configured to transmit the resulting torque to the transmission shaft 26.

[0032] The transmission shaft 26 naturally comprises a first half-shaft and a second half-shaft, the two half-shafts being mechanically connected via the differential 28. The differential 28 then transmits the resulting torque to each of the two half-shafts of the transmission shaft 26. Conversely, each half-shaft can transmit a torque to the differential 28.

[0033] In the embodiment described here, the first crown 20 is advantageously arranged between the fixed part 8 of the first rotating machine 6 and the fixed part 14 of the second rotating machine 12. In such a configuration, each rotating machine 6, 12 is positioned axially on a given side of the differential 28 and of the first epicyclic gear train to transmit the first mechanical torque and the second mechanical torque to the differential 28.

[0034] The drive device 2 allows the transmission shaft 26 to be driven in rotation using two rotating machines 6, 12, rotating in the same direction. In such a configuration, the reliability of such a drive device 2 is significantly increased, the transmission shaft 26 being able to be driven despite a possible failure of one of the two rotating machines 6, 12. Indeed, in the case of a failure of the first rotating machine 6, the wheels 3 receive a torque resulting from the transmission shaft equivalent to the second mechanical torque, generated by the second rotating machine 12. Conversely, in the case of a failure of the second rotating machine 12, the wheels 3 receive a torque resulting from the transmission shaft equivalent to the first mechanical torque, generated by the first rotating machine 6.

[0035] In the embodiment described here, the moving part 10 of the first rotating machine 6 and the moving part 16 of the second rotating machine 12 are coaxial.

[0036] Here, the differential 28 is advantageously arranged radially inside the first epicyclic gear train 18, improving the compactness of the drive device 2.

[0037] In the embodiment described in [Fig. 1], the moving part 16 of the second rotating machine 12 is integral in rotation with the transmission shaft. The resulting torque transmitted to the transmission shaft 26 is then the sum of the first mechanical torque generated by the first rotating machine 6 and the second mechanical torque generated by the second rotating machine 12. Thus, it is possible to obtain a higher resulting mechanical torque, in particular by controlling the two rotating machines 6, 12 so that each operates at an operating point maximizing its efficiency. The term "operating point" means the configuration of an electrical machine at a given rotational speed for a given mechanical torque.In this configuration, the second torque is then transmitted to the differential 28 via the transmission shaft 26, in particular to transmit the resulting torque to the half-shaft axially opposite the second machine 12 relative to the differential 28.

[0038] [Fig. 2] describes the drive device 2 according to a second embodiment. The drive device described in [Fig. 2] differs from that shown in [Fig. 1], in that the moving part 16 of the second rotating machine 12 is integral in rotation with the planet carrier 24 of the first epicyclic gear set 18. The resulting torque is then transmitted to the differential 28 entirely via the first epicyclic gear set 18. The resulting torque transmitted to the transmission shaft 26 is the sum of the mechanical torques of the first machine and the second machine. The two rotating machines 6, 12 rotate the same mechanical element. Thus, the distribution of a mechanical torque on the transmission shaft 26 is carried out at different application points, promoting the service life of the transmission shaft.The torque transmission is carried out between the second machine and the transmission shaft 26 is carried out without an additional reducer. In this embodiment, both machines rotate at the same speed.

[0039] [Fig. 3] illustrates the drive device 1 according to a variant of the embodiment of [Fig. 1], and [Fig. 4] illustrates the drive device 1 according to a variant of the embodiment of [Fig. 2]. In [Fig. 3] and in [Fig. 4], the first rotating machine 6 and the second rotating machine 6 are axial flux electrical machines. In this configuration, the fixed part 8 of the first machine 6 comprises at least one stator 30 secured to the frame 4, and the mobile part 10 of the first machine 6 comprises at least one rotor 32 configured to transmit the first mechanical torque. The fixed part 8 of the first machine 6 may comprise two stators 30 which frame the rotor 32. The mobile part 10 of the first machine 6 may comprise several rotors 32, each being framed by the two stators 30. Each rotor 32 may comprise permanent magnets that do not require any external excitation. The stators 30 have, for example, a half-cylinder shape, and may be fixed so as to entirely surround the rotor(s) 30, in particular by means of a radial fold of each of the half-cylinders. One of the stators 30 may be secured to the frame 4 or alternatively, each of the stators 30 is secured directly to the frame 4, for example arranged in a casing of the frame 4.

[0040] The fixed part 14 of the second machine 12 comprises at least one stator 34 secured to the frame 4, and the mobile part 16 of the second machine 12 comprises at least one rotor 36 configured to transmit the first mechanical torque. The fixed part 14 of the second machine 12 may comprise two stators 34 which frame the rotor 36. The mobile part 16 of the second machine 12 may comprise several rotors 36, each being framed by the two stators 34. Each rotor 36 may comprise permanent magnets which do not require any external excitation. The stators 34 have, for example, a half-cylinder shape, and may be fixed so as to entirely frame the rotor(s) 36, in particular by means of a radial fold of each of the half-cylinders. One of the stators 34 may be integral with the frame 4 or alternatively, each of the stators 34 is directly integral with the frame 4, for example arranged in a casing of the frame 4.

[0041] It will also be noted that the invention is not limited to the embodiments described above. It will indeed appear to those skilled in the art that various modifications can be made to the embodiment described above, in light of the teaching which has just been disclosed to them.

[0042] For example, in the embodiment described in [Fig.l], an additional reducer (not shown) may be arranged between the moving part 16 of the second rotating machine 12 and the transmission shaft 26. The reducer may for example be a second epicyclic gear train.

[0043] The drive device 1 may also comprise bearings, for example mechanical bearings such as ball or roller bearings (not shown). In the variant described in [Fig. 3], a first bearing may advantageously be arranged between the stator 30 and the planet carrier 24 of the first machine 6, that is to say that an inner ring of said first bearing is integral with the planet carrier 24 and that an outer ring of said first bearing is integral with the stator 30 of the first machine 6. A second bearing may advantageously be arranged between the stator 34 of the second machine 12 and the transmission shaft 26, that is to say that an inner ring of said second bearing is integral with the transmission shaft 26 and that an outer ring is integral with the stator 34 of the second machine 12.

[0044] In the variant described in [Fig.4], each bearing can advantageously be arranged between the stators 30, 34 and the planet carrier 24, that is to say that an inner ring of each bearing is integral with the planet carrier 24 and that an outer ring of each bearing is integral with the stators 30, 34.

[0045] In the detailed presentation of the invention which is made above, the terms used must not be interpreted as limiting the invention to the embodiment set out in the present description, but must be interpreted to include all equivalents whose prediction is within the reach of a person skilled in the art by applying his general knowledge to the implementation of the teaching which has just been disclosed to him.

Claims

Claims

1. Mechanical drive device (2) comprising: • a frame (4); • a first rotating machine (6) comprising a fixed part (8) secured to the frame (4) and a rotating part (10) configured to transmit a first mechanical torque; • a second rotating machine (12) comprising a fixed part (14) secured to the frame (4) and a rotating part (16) configured to transmit a second mechanical torque; • a first epicyclic gear train (18) comprising a first crown (20) secured to the frame (4), a sun gear (22) rotatable relative to the crown (20) and a planet carrier (24) rotatable relative to the crown (20), the movable part (10) of the first rotating machine (8) being rotatable with the planet carrier (24) of the epicyclic gear train (18); • a transmission shaft (26) configured to transmit a resulting torque;• a differential (28) arranged between the first epicyclic gear set (18) and the transmission shaft (26) in the direction of torque transmission, comprising a second crown gear integral in rotation with the sun gear (22) of the first epicyclic gear set (18), the differential (28) being configured to transmit a resulting torque to the transmission shaft (26), the drive device (2) being characterized in that the movable part (16) of the second rotating machine (12) transmits the second torque to the differential (28).;

2. Drive device (2) according to claim 1, the first crown (20) being arranged between the fixed part (8) of the first machine (6) and the fixed part (14) of the second machine (12).

3. Drive device (2) according to claim 1 or 2, in which the movable part (16) of the second rotating machine (12) is rotationally integral with the transmission shaft (26).

4. Drive device (2) according to claim 3, comprising a reducer connecting the movable part (16) of the second rotating machine (12) to the transmission shaft (26).

5. Drive device (2) according to claim 1 or 2, in which the movable part (16) of the second rotating machine (12) is rotationally secured to the planet carrier (24) of the first epicyclic gear train (18).

6. A drive device (2) according to any preceding claim, wherein the movable part (10) of the first rotating machine (6) and the movable part (16) of the second rotating machine (12) are coaxial.

7. A drive device (2) according to any preceding claim, wherein the differential (28) is radially arranged inside the first epicyclic gear train (18).

8. A drive device (2) according to any preceding claim, wherein the first rotating machine (6) is an axial flux electric motor.

9. A drive device (2) according to any preceding claim, wherein the second rotating machine (12) is an axial flux electric motor or a wheel motor.

10. An electric vehicle comprising a drive device (2) according to any one of claims 1 to 9.

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