Electric powertrain for a motor vehicle

Abstract

The invention relates to an electric powertrain (1) for a motor vehicle (2), the electric powertrain comprising: - a reversible electric machine (30) comprising a rotor (31) rotatable about a machine axis (X); - an inverter (50) supplying an electric current to the electric machine; - a speed reducer (40) kinematically linked to the rotor (31) of the reversible electric machine; - a gearbox (45) at least partially supporting the reversible electric machine and / or the inverter and / or the speed reducer; - a closing cover (10, 10a, 10b) attached to a cavity (5) formed on one of the elements of the electric powertrain selected from among the reversible electric machine, the inverter, the speed reducer or the gearbox; - a device (20) for supporting the electric powertrain arranged so as to be attached to the chassis of the motor vehicle, wherein the chassis at least partially covers the closing cover.

Description

Description Technical field

[0001] The invention relates to the field of motor vehicle powertrains, in particular electric powertrains. This type of powertrain generally comprises a reversible electric machine and a speed reducer connecting said electric machine to the wheels of the vehicle.

[0002] Due to the excitations of the speed reducer and the reversible electric machine, the structural elements of a powertrain, more particularly the external surfaces, can vibrate in their own mode and propagate noise towards the inside or outside of the motorized vehicle, for example a motor vehicle or an industrial vehicle. For example, when a transmission housing closing cover has vibration modes with natural frequencies close to the excitation frequencies, the noise levels are amplified.

[0003] To combat vibrations, it is known to equip powertrains with suspension mounts, particularly between the casing of the electric machine and the vehicle chassis. Suspension mounts are generally installed on the most rigid parts of the casing. However, they are only effective against vibrations within a limited frequency range. In addition, the space available around the powertrain is limited, which makes the installation of this type of suspension mount difficult.

[0004] An electric powertrain as described in German patent application DE102021214776 A1 comprises a reversible electric machine and a speed reducer integrated within a transmission housing. In order to control the electric machine, an electric current inverter integrates electronic components for managing the electrical power according to the vehicle's needs. The electronic components of the inverter are supported by the transmission housing and protected by a closing cover attached and fixed to the transmission housing. The closing cover includes in particular a rigid fixing perimeter and a thin wall which can vibrate under the effect of its natural frequency. The noise generated by the vibrations of the electric machine and the speed reducer is transmitted through the surface of the closing cover.

[0005] The objective of the invention is to treat the vibrations generated by the closing hood whose natural frequency is generally greater than 200Hz. By extension, the objective of the invention is to treat the vibrations generated by all the structural elements of a powertrain.

[0006] The present invention also aims to provide a vibration reduction solution for the electric powertrain, the installation of which would be facilitated within the motorized vehicle.

[0007] According to a first aspect, the invention relates to an electric powertrain for a motorized vehicle comprising: - a reversible electric machine comprising a rotor mobile in rotation around a machine axis X; - an electric current inverter supplying the electric machine; - a speed reducer kinematically linked to the rotor of the reversible electric machine; - a transmission casing at least partially supporting the reversible electric machine and / or the inverter and / or the speed reducer; - a closing cover attached to a cavity formed on one of the elements of the electric powertrain chosen from the reversible electric machine, the inverter, the speed reducer or the transmission casing; - an electric powertrain support device arranged to be fixed to the chassis of the motorized vehicle which at least partially covers the closing hood.

[0008] The electric powertrain is remarkable in that an elastomer element is interposed between the support device and one of the closing covers of the electric powertrain, the elastomer element, which simultaneously presses on the closing cover and the support device, is fixed either on the closing cover or on the support device.

[0009] The interposition of this elastomer element makes it possible to cancel the low-frequency excitation modes linked to thin covers obtained by molding or stamping and limits the acoustic radiation of the electric powertrain. The interposition of this elastomer element between the support device and the closing cover does not impact the overall size of the electric powertrain.

[0010] The noise emitted by acoustic radiation from a so-called "flexible" area of ​​a closing hood subject to mechanical vibration, for example from the electrical machine, can be detrimental to the comfort of the passengers of the motor vehicle. so-called "flexible" zone is for example a large flat zone or a zone of low stiffness compared to the mechanical forces to which it is subjected. In order to limit acoustic radiation, the invention aims to insert an elastomer element between a so-called "flexible" zone of the electric powertrain and a so-called "rigid" zone of the support device. The support device covers the closing hood so that there is at least partial geometric overlap of these two components.

[0011] The closing cover can be attached, for example, to an inverter of the electric powertrain or to a cavity of the speed reducer or the reversible electric machine. The closing cover can support the transmission shafts and guide bearings of the speed reducer. Thus, the closing cover can be a structural element of the electric powertrain.

[0012] Advantageously, the support device may comprise fixing zones with the electric powertrain, the elastomer element being arranged between said fixing zones.

[0013] Preferably, the support device may comprise a plate connecting the different fixing zones and a suspension arm on which a damping sleeve is inserted, the damping sleeve is arranged on a receiving zone of the support device.

[0014] Advantageously, the closing hood can partly form the cavity.

[0015] Preferably, the axial stiffness in N / mm of the support device measured at the point of contact with the elastomer element is at least five times greater than the stiffness of the closing cap measured at the point of contact with the elastomer element, the measuring axis being normal to the contact surface of the closing cap.

[0016] The invention may have one or other of the characteristics described below combined with each other or taken independently of each other. - the support device covers the closing hood according to a geometric plane, for example perpendicular to the machine axis X. This limits the acoustic radiation of the closing hood. - the support device covers the closing hood circumferentially. - the elastomer element comprises a fixing base and at least one support zone, the support zone being punctual or widened or formed from a series of separate supports. - the point support zone has an area less than or equal to 1 cm 2 . - the enlarged support zone has an area greater than 1 cm 2 . - the elastomer element is for example attached by gluing, vulcanization or overmolding. - the elastomer element is for example made of rubber, or neoprene or another synthetic material having elastic compression properties. - the receiving area of ​​the support device is a flat surface which includes a drilling-tapping along a secondary axis X2 perpendicular to this flat surface. - the receiving area is arranged on a free end of the support device furthest from the closing hood. - according to a variant of the invention, the secondary axis X2 is parallel to the machine axis X. - according to another variant of the invention, the secondary axis X2 is perpendicular to the machine axis X. - according to yet another variant of the invention, the receiving zone of the support device is a cylindrical bore along a secondary axis X2 oriented perpendicular to the machine axis X. - the plate of the support device is stiffened using stiffening ribs, the elastomer element being held in position by means of the stiffening ribs. - the stiffening ribs extend from the internal face of the plate towards the closing cover. - the elastomer element rests on the plate in a rigid area located to the right of the suspension arm. - the support device comprises at least one stiffening rib connecting the suspension arm to the plate. - a fixing screw is inserted into a bore in the damping sleeve and screwed into a tapped hole in the suspension arm. - the plate of the support device comprises an internal face arranged opposite the closing cover. - the support zone is in direct contact with the internal face of the plate of the support device. - the closing cover is fixed to the element of the electric powertrain which includes the cavity using fixing screws. - the elastomer element comprises an annular portion whose inner bore at least partially surrounds the closing cap. - the closing cover closes a cavity of the speed reducer or the transmission housing and supports a radial guide bearing according to a first geometric plane perpendicular to the axis of rotation of the bearing, the elastomer element surrounds the closing cover in the material zone crossed by the first geometric plane. - the radial guide bearing is a ball bearing or a roller bearing or a needle bearing. - the radial guide bearing supports a transmission shaft of the speed reducer or the rotor of the reversible electric machine. - the closing cover comprises a closing wall and a fixing perimeter resting on the electric powertrain, the support zone of the elastomer element being arranged inside this fixing perimeter. - the flat interface area includes an insertion groove for a seal. - the support device includes stiffening stampings. - the closing hood is obtained by mechanical welding, casting or machining.

[0017] The invention applies, for example, to the closing hood made of stamped sheet metal, the thickness of which can be between 0.5 mm and 3 mm.

[0018] The invention applies, for example, to the closing hood made from cast aluminium, the variable thickness of which can be between 2 mm and 10 mm.

[0019] Each of these features helps limit the solution's footprint. Without adding additional geometric constraints to the electric powertrain, it is possible to cancel out the low-frequency excitation modes associated with thin covers obtained by molding or stamping. This limits the acoustic radiation of the electric powertrain. Brief description of the figures

[0020] The invention will be better understood, and other objects, details, characteristics and advantages thereof will appear more clearly during the following description of several particular embodiments of the invention, given solely for illustrative and non-limiting purposes, with reference to the accompanying drawings.

[0021] [fig.1] Figure 1 represents an electric powertrain comprising a closing hood according to a first embodiment of the invention.

[0022] [fig.2] Figure 2 represents an electric powertrain comprising a closing hood according to a second embodiment of the invention. Description of the embodiments

[0023] Figure 1 illustrates an electric powertrain 1 for a motorized vehicle according to a first embodiment of the invention, comprising a reversible electric machine 30 comprising a stator (not shown), a rotor 31 movable in rotation about a machine axis X, an inverter 50 of electric current supplying the electric machine and a speed reducer 40 kinematically linked to the rotor 31 of the reversible electric machine. The output shaft of the speed reducer drives a set of one or more drive wheels of the motorized vehicle, in this case a motor vehicle.

[0024] The speed reducer 40 housed inside a cavity of the transmission casing comprises transmission shafts to which toothed wheels are rotationally secured to achieve a speed reduction ratio between the rotor of the electric machine and the output shaft of the speed reducer. The speed reducer is itself protected from the external environment by a closing cover.

[0025] The reversible electric machine 30, the speed reducer 40 and the inverter 50 are supported by a transmission casing 45. The electric powertrain 1 is fixed to the chassis of the vehicle by means of at least one support 4 and a support device 20 assembled with a damping sleeve 3 of cylindrical shape.

[0026] The support device 20 is rigidly fixed to the transmission housing 45 using fixing screws 29a. The damping sleeve 3 reliably connects the support device 20 to the support 4 while allowing a certain flexibility in this connection in order to provide a damping function. The damping sleeve 3 is made, for example, of elastomeric material.

[0027] According to the invention, the support device 20 can be attached to any type of element of the electric powertrain 1 mentioned in this description.

[0028] In this first embodiment of the invention, the cavity 5 of the electric machine is closed by a closing cover 10 comprising a fixing perimeter 11 and a closing wall 13. The closing cover 10 protects an electronic card 9 contained in the cavity 5. The closing cover 10 is fixed to the element of the electric powertrain which comprises the cavity 5 using fixing screws 8.

[0029] The fixing perimeter 11 of the closing cover rests on a complementary perimeter arranged on the transmission casing. The fixing perimeter 11 comprises a flat interface zone 11a with the electric powertrain. In addition, a seal is arranged between the two fixing perimeters. The fixing by fixing screw of the closing cover, the crushing of the seal and the assembly of the fixing perimeter 11 on the transmission casing guarantees a seal of the powertrain in this zone.

[0030] The support device 20 comprises fixing zones 29 with the electric powertrain on which the fixing screws 29a are housed. The support device 20 also comprises a plate 23 connecting the different fixing zones 29 and a suspension arm 21 on which the damping sleeve 3 is inserted, the damping sleeve 3 being arranged on a receiving zone 22 of the support device. The receiving zone 22 is perpendicular to this flat interface zone 11a of the closing cover. The receiving zone 22 is arranged on the free end of the support device furthest from the fixing periphery 11.

[0031] The support device 20 comprises a tapped hole 27 along a secondary axis X2 opening into the receiving zone 22. A fixing screw 28 is inserted into a bore of the elastomer element 3 and screwed into a tapped hole 27 of the suspension arm 21. A stiffening rib connects the support device 20 to the plate 23. Other stiffening ribs 25 of the support device extend from the internal face 26 of the plate 23 in the direction of the fixing periphery 11 of the closing cover 10.

[0032] According to the invention, an elastomer element 70 is interposed between the support device 20 and the closing cap 10. The elastomer element 70 bears simultaneously on the support device 20 and the closing cap 10. In this first embodiment, the elastomer element is fixed to the support device. The damping sleeve 3 and the elastomer element 70 are separate components.

[0033] The interposition of this elastomer element makes it possible to cancel the low-frequency excitation modes linked to the closing cover obtained by molding. More precisely, the elastomer element 70 is interposed axially relative to the machine axis X between the closing wall 13, similar to a so-called “flexible” zone of the closing cover, and the end of the stiffening ribs 25, similar to a so-called “rigid” zone of the support device 20.

[0034] As illustrated in figure 1, the elastomer element 70 comprises a fixing base 71 and a support zone 72 having an enlarged shape given that this support zone has a surface area greater than 1 cm 2 .

[0035] To facilitate assembly, the elastomer element 70 is held in position by means of the stiffening ribs 25. The shape of the fixing base 71 is complementary to the shape of the stiffening ribs which form a receiving housing for the elastomer element. For example, the support zone 72 may cover several stiffening ribs.

[0036] When assembling the support device 20 on the electric powertrain 1, the crushing of the elastomer element 70 is calculated as a function of the flexibility of the closing wall 13 of the closing cover.

[0037] In this first embodiment, the support device 20 covers the closing hood 10 along a geometric plane perpendicular to the machine axis X.

[0038] The axial stiffness in N / mm of the support device 20 measured along the machine axis X at the point of contact with the elastomer element 70 is here ten times greater than the stiffness of the closing hood 10 measured along the same machine axis X at the point of contact with the elastomer element 70. The machine axis X is normal to the contact surface of the closing hood 10.

[0039] Figure 2 shows a diagram of a second embodiment of the invention which differs from the first embodiment in that the closing cover 10b directly supports a transmission shaft and a guide bearing of the speed reducer and in that the support device 20 covers the closing cover 10b circumferentially.

[0040] In this second embodiment, the cavity 5 of the speed reducer 40 is closed by a closing cover 10b comprising a fixing perimeter 11 and a closing wall 13. The closing cover 10b protects a gear train contained in the cavity 5, more particularly a transmission shaft 41 with an axis of rotation X3. The closing cover 10b is fixed to the element of the electric powertrain which comprises the cavity 5 using fixing screws 8.

[0041] The support device 20 comprises fixing zones 29 with the electric powertrain on which fixing screws 29a are housed. The support device 20 also comprises a plate 23 connecting the different fixing zones 29 and a suspension arm 21 in which a damping sleeve 3 is inserted, the damping sleeve 3 being arranged on a receiving zone 22 of the device support. The plate 23 of the support device comprises an internal face 26 arranged directly opposite the closing cover. The receiving zone 22 is a cylindrical bore along a secondary axis X2 oriented perpendicular to the axis of rotation X3 which is parallel to the machine axis X. The receiving zone 22 is arranged on the free end of the support device furthest from the fixing circumference 11.

[0042] The closing cap 10b supports a radial guide bearing 42 along a first geometric plane P1 perpendicular to the axis of rotation X3 of the bearing and an elastomer element 70a surrounds the closing cap 10b in the material zone crossed by the first geometric plane P1. The elastomer element 70a comprises in particular an annular portion whose internal bore 73 at least partially surrounds the closing cap 10b. The internal bore 73 forms the base of the elastomer element 70a which also comprises a support zone 72 formed of a series of separate supports. The supports are for example distributed angularly around the axis of rotation X3.

[0043] The radial guide bearing 42 is a ball bearing which supports the transmission shaft 41 of the speed reducer. This transmission shaft 41 transmits mechanical vibrations which tend to cause the closing hood to vibrate.

[0044] The closing hood here comprises a circular receiving surface which is complementary to the annular shape of the elastomer element 70a. Thanks to the elastomer element 70a, these vibrations are attenuated.

[0045] In this second embodiment, a second elastomer element 70b is interposed between the support device 20 and the closing cover 10b. The elastomer element 70b is fixed to the closing cover using a fixing screw and rests on the plate 23 in a rigid zone located at the right of the suspension arm 21.

[0046] This second elastomer element 70b comprises a fixing base 71 and a support zone 72 having a point shape given that this support zone has a surface area less than or equal to 1 cm 2 The support zone 72 is directly in contact with the internal face 26 of the plate 23 of the support device.

[0047] In this example, the axial stiffness in N / mm of the support device 20 measured at the point of contact with the elastomer element 70b is five times greater than the stiffness of the closing cap 10b measured at the point of contact with the elastomer element 70b, the measuring axis being normal to the contact surface of the closing cap. The measuring axis here is the rotation axis X3.

[0048] Although the invention has been described in connection with several particular embodiments, it is obvious that it is in no way limited thereto and that it includes all the technical equivalents of the means described as well as their combinations if these fall within the scope of the invention, as defined by the claims.

[0049] The closing cover may also have other functions other than that of ensuring the sealing of a cavity formed on one of the elements of the electric powertrain and may for example support a transmission shaft or channel and direct a flow of cooling oil contained within the electric powertrain.

[0050] In the claims, any reference sign in parentheses cannot be interpreted as a limitation of the claim.

Claims

Claims 1. Electric powertrain (1) for motorized vehicle comprising: - a reversible electric machine (30) comprising a rotor (31) movable in rotation around a machine axis (X); - an electric current inverter (50) supplying the electric machine; - a speed reducer (40) kinematically linked to the rotor (31) of the reversible electric machine; - a transmission casing (45) at least partially supporting the reversible electric machine and / or the inverter and / or the speed reducer; - a closing cover (10, 10a, 10b) attached to a cavity (5) formed on one of the elements of the electric powertrain chosen from the reversible electric machine, the inverter, the speed reducer or the transmission casing; - a support device (20) for the electric powertrain arranged to be fixed to the chassis of the motorized vehicle which at least partially covers the closing hood; characterized in that an elastomer element (70, 70a, 70b) is interposed between the support device (20) and one of the closing hoods (10, 10a, 10b) of the electric powertrain, the elastomer element, which simultaneously presses on the closing hood and the support device, is fixed either on the closing hood or on the support device.

2. Electric powertrain (1) according to claim 1, wherein the support device (20) comprises fixing zones (29) with the electric powertrain (1), the elastomer element (70, 70a, 70b) is arranged between said fixing zones (29).

3. Electric powertrain (1) according to one of the preceding claims, in which the closing cover (10, 10a, 10b) comprises a closing wall (13) and a fixing circumference (11) bearing on the electric powertrain, the bearing zone (72) of the elastomer element being arranged inside this fixing circumference.

4. Electric powertrain (1) according to claim 2, wherein the support device (20) comprises a plate (23) connecting the different fixing zones (29) and a suspension arm (21) on which a sleeve is inserted. damping sleeve (3), the damping sleeve is arranged on a receiving area (22) of the support device (20).

5. Electric powertrain (1) according to the preceding claim, in which the receiving zone (22) is a cylindrical bore (22) along a secondary axis (X2) oriented perpendicular to the machine axis (X).

6. Electric powertrain (1) according to one of the preceding claims, in which the elastomer element (70) comprises a fixing base (71) and at least one support zone (72), the support zone (72) being punctual or widened or formed of a series of separate supports.

7. Electric powertrain (1) according to one of claims 4 to 6, in which the plate (23) is stiffened using stiffening ribs (25), the elastomer element (70) being held in position by means of the stiffening ribs (25).

8. Electric powertrain (1) according to the preceding claim, in which the elastomer element (70) rests on the plate (23) in a rigid zone located at right angles to the suspension arm (21).

9. Electric powertrain (1) according to the preceding claim, comprising at least one stiffening rib (25) connecting the suspension arm (21) to the plate (23).

10. Electric powertrain (1) according to one of claims 4 to 9, wherein a fixing screw (28) is inserted into a bore of the damping sleeve (3) and screwed into a tapped hole of the suspension arm (21).

11. Electric powertrain (1) according to one of claims 4 to 10, in which the plate (23) of the support device (20) comprises an internal face (26) arranged opposite the cavity (5).

12. Electric powertrain (1) according to claim 7, wherein the stiffening ribs (25) extend from the inner face (26) of the plate (23) towards the closing cover (10).

13. Electric powertrain (1) according to one of the preceding claims, in which the elastomer element (70a) comprises an annular portion whose inner bore (73) at least partially surrounds the closing cover.

14. Electric powertrain (1) according to one of the preceding claims, in which the closing cover (10b) closes a cavity (5) of the speed reducer or of the transmission housing and supports a radial guide bearing (42) according to a first geometric plane (P1) perpendicular to the axis of rotation of the bearing (X3), the elastomer element (70) surrounds the closing cover in the material zone crossed by the first geometric plane (P1).

15. Electric powertrain (1) according to the preceding claim, wherein the radial guide bearing (42) supports a transmission shaft (41) of the speed reducer (40) or the rotor (31) of the reversible electric machine (30).

16. Electric powertrain (1) according to one of the preceding claims, wherein the axial stiffness in N / mm of the support device (20) measured at the point of contact with the elastomer element (70, 70a, 70b) is at least five times greater than the stiffness of the closing cap (10, 10a, 10b) measured at the point of contact with the elastomer element, the measuring axis being normal to the contact surface of the closing cap.

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