Electric power train for a motor vehicle

Abstract

The invention relates to an electric drive train (1) for a motor vehicle (2), comprising:-a reversible electric machine (30) comprising a rotor (31) rotatable about a machine axis (X); -an inverter (50) which supplies 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) which at least partially supports the reversible electric machine and / or the inverter and / or the decelerator; -a closure cover (10, 10a, 10b) attached to a cavity (5) formed on one of the elements of the electric powertrain, selected from the group consisting of a reversible electric machine, an inverter, a decelerator or a gearbox; -means (20) for supporting the electric power train, said means being arranged to be attached to the chassis of the motor vehicle, said means at least partially covering the closure cover.

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of motor vehicle powertrains, in particular electric powertrains. A powertrain of this type generally comprises a reversible electric machine and a reduction gear connecting said electric machine to the wheels of the vehicle. BACKGROUND

[0002] Due to the excitation of the reduction gear and of the reversible electric machine, structural elements of the powertrain, more particularly outer surfaces, can vibrate in their natural modes and transmit noise to the interior or exterior of the motor vehicle, for example a motor vehicle or an industrial vehicle. For example, when the transmission housing closure cover has a vibration mode with a natural frequency close to the excitation frequency, the noise level is amplified.

[0003] To combat the vibrations, it is known practice to fit the powertrain with suspension mounts arranged between the electric machine housing and the vehicle chassis. The suspension mounts are generally mounted on the most rigid part of the housing. However, they are only effective against vibrations in a limited frequency range. In addition, the available space around the powertrain is limited, so it is difficult to install suspension mounts of this type.

[0004] The electric powertrain described in German patent application DE 102021214776 A1 comprises a reversible electric machine and a reduction gear integrated within a transmission housing. To control the electric machine, a current inverter contains electronic components for managing the electric power according to the requirements of the vehicle. The electronic components of the inverter are supported by the transmission housing and are protected by a closure cover attached and fixed to the transmission housing. The closure cover in particular comprises a rigid fixed rim and a thin wall which can vibrate under the action of its natural frequency. The noise generated by the vibrations of the electric machine and of the reduction gear is transmitted via the surface of the closure cover. SUMMARY

[0005] The aim of the present invention is to treat the vibrations generated by the closure cover, the natural frequency of which is generally greater than 200 Hz. By extension, the aim of the present invention is to treat the vibrations generated by all the structural elements of the powertrain.

[0006] Another aim of the present invention is to provide a vibration damping solution for an electric powertrain which will be convenient to install within a motor vehicle.

[0007] According to a first aspect, the invention relates to an electric powertrain for a motor vehicle, comprising:

[0008] - a reversible electric machine comprising a rotor rotatable about a machine axis X;

[0009] - a current inverter supplying the electric machine with electric power;

[0010] - a reduction gear kinematically connected to the rotor of the reversible electric machine;

[0011] - A transmission housing that at least partially supports a reversible motor and / or an inverter and / or a reducer;

[0012] - A closed cover, which is attached to a cavity formed on one of the elements of an electric power transmission system, the element being selected from a reversible motor, inverter, reducer or transmission housing;

[0013] - A support device for supporting an electric powertrain, designed to be fixed to the chassis of a motor vehicle and at least partially cover the closed cover.

[0014] The notable feature of the electric drive system is that the elastomeric element is inserted between the support device and one of the closed covers of the electric drive system, while the elastomeric element supported on the closed cover and the support device is fixed to the closed cover or the support device.

[0015] The insertion of this elastomeric element eliminates low-frequency excitation modes associated with thin caps obtained through molding or stamping, and limits acoustic radiation from the electric drive system. The insertion of this elastomeric element between the support and the closing cap does not affect the overall dimensions of the electric drive system.

[0016] The so-called "flexible" area of ​​the closed cover, subjected to acoustic radiation noise from sources such as mechanical vibrations from the motor, can impair the comfort of motor vehicle passengers. The so-called "flexible" area is, for example, a flat area with a large size or a low stiffness compared to the mechanical forces it experiences. To limit acoustic radiation, the object of the present invention is to insert an elastomeric element between the so-called "flexible" area of ​​the electric powertrain and the so-called "rigid" area of ​​the support device. The support device covers the closed cover such that there is at least partial geometric overlap between the two components.

[0017] The cover can be attached, for example, to the inverter of an electric drive system or to the cavity of a gearbox or reversible motor. The cover can support the drive shaft and guide bearing of the gearbox. Therefore, the cover can be a structural element of an electric drive system.

[0018] Advantageously, the support device may include fixed regions for fixing to the electric power transmission system, with elastomeric elements arranged between the fixed regions.

[0019] Preferably, the support device may include a plate connecting the various fixed areas and a suspension arm, with a damping sleeve inserted into the suspension arm and arranged on the receiving area of ​​the support device.

[0020] Advantageously, the closed cap can partially form a cavity.

[0021] Preferably, the axial stiffness (in N / mm) of the support device measured at the contact point with the elastomer element is at least five times greater than the stiffness of the closed cover measured at the contact point with the elastomer element, and the measuring axis is perpendicular to the contact surface of the closed cover.

[0022] The present invention may have one or more of the following features, either in combination or independently of each other:

[0023] - The support structure covers the closed cover in a geometric plane, for example, perpendicular to the machine's axis X. This limits the acoustic radiation from the closed cover.

[0024] -The support device covers the closed cover circumferentially.

[0025] - An elastomeric element includes a fixed base and at least one support region, which may be a point, an enlarged area, or formed by a series of different support surfaces.

[0026] - The point support area has a surface area of ​​less than or equal to 1 square centimeter.

[0027] - The enlarged support area has a surface area greater than 1 square centimeter.

[0028] - Elastomer elements are attached, for example, by adhesive bonding, vulcanization, or overmolding.

[0029] - Elastomers are made of, for example, rubber, or neoprene, or another synthetic material with elastic compression properties.

[0030] - The receiving area of ​​the support device is a flat surface, which includes a threaded hole along a secondary axis X2 perpendicular to the flat surface.

[0031] - The receiving area is located on the free end of the support device that is furthest from the closed cover.

[0032] -According to a variation of the invention, the secondary axis X2 is parallel to the machine axis X.

[0033] - According to another variation of the invention, the secondary axis X2 is perpendicular to the machine axis X.

[0034] -According to another variation of the invention, the receiving area of ​​the support device is a cylindrical hole along a secondary axis X2 oriented perpendicular to the machine axis X.

[0035] - The support plate is reinforced by reinforcing ribs, and the elastomeric elements are held in place by reinforcing ribs.

[0036] - The reinforcing ribs extend from the inner surface of the plate in the direction of the closed cover.

[0037] - The elastomeric element is supported on the plate in a rigid region that is aligned with the suspension arm.

[0038] - The support device includes at least one reinforcing rib that connects the suspension arm to the plate.

[0039] Insert the fixing screw into the hole of the damping sleeve and screw it into the threaded hole of the suspension arm.

[0040] - The plate of the support device includes an inner surface facing the closed cover.

[0041] - The support area is in direct contact with the inner surface of the plate of the support device.

[0042] - The closing cover is fixed to the cavity-containing element of the electric power transmission system by fixing screws.

[0043] - The elastomeric element includes an annular portion whose inner bore at least partially surrounds the closing cap.

[0044] - The closing cover encloses the cavity of the reducer or transmission housing and supports the radial guide bearing in a first geometric plane perpendicular to the axis of rotation of the bearing. The elastomeric element surrounds the closing cover in a material region through which the first geometric plane passes.

[0045] -Radial guide bearings are ball bearings, roller bearings, or needle roller bearings.

[0046] - Radial guide bearings support the drive shaft of the reducer or the rotor of a reversible motor.

[0047] - The closing cover includes a closing wall and a fixed edge supported on the electric power transmission system, and the support area of ​​the elastomeric element is arranged within the fixed edge.

[0048] - The flat interface area includes insertion grooves for the seal.

[0049] - The support device includes reinforced stamped components.

[0050] - The closure is obtained through mechanical welding, casting, or machining.

[0051] The present invention is applicable, for example, to closures made of stamped metal sheets, the thickness of which can be between 0.5 mm and 3 mm.

[0052] The present invention is applicable, for example, to closures made of cast aluminum, with a variable thickness that can be between 2 mm and 10 mm.

[0053] Each of these characteristics allows for the restriction of the solution volume. Low-frequency excitation modes associated with thin caps obtained through molding or stamping can be eliminated without adding any additional geometric constraints to the electric drive system. This limits the acoustic radiation of the electric drive system. Attached Figure Description

[0054] The invention will be better understood in the following description of several specific embodiments of the invention, given only by way of non-limiting description, with reference to the accompanying drawings, and other objects, details, features and advantages of the invention will become clearer.

[0055] [ Figure 1 ] Figure 1 An electric power transmission system including a closing cover according to a first embodiment of the present invention is shown.

[0056] [ Figure 2 ] Figure 2 An electric power transmission system including a closing cover according to a second embodiment of the invention is shown. Detailed Implementation

[0057] Figure 1 An electric powertrain 1 for a motor vehicle according to a first embodiment of the present invention is shown, comprising: a reversible motor 30 including a stator (not shown), a rotor 31 rotatable about a machine axis X; a current inverter 50 supplying power to the motor; and a reducer 40 kinetically connected to the rotor 31 of the reversible motor. The output shaft of the reducer drives one or more sets of drive wheels of the motor vehicle (in the present case, an automobile).

[0058] The reducer 40 is housed within the cavity of the gearbox housing and includes a drive shaft on which gears are rotatably fixed to achieve a reduction ratio between the motor rotor and the reducer output shaft. The reducer itself is protected from external environmental influences by a closed cover.

[0059] The reversible motor 30, reducer 40, and inverter 50 are supported by the transmission housing 45. The electric powertrain 1 is fixed to the vehicle chassis by at least one support member 4 and a support device 20 with a cylindrical damping sleeve 3 assembled on it.

[0060] The support device 20 is rigidly fixed to the transmission housing 45 by means of fixing screws 29a. A damping sleeve 3 reliably connects the support device 20 to the support member 4, while allowing a degree of flexibility in this connection to ensure damping function. The damping sleeve 3 is made, for example, of an elastomeric material.

[0061] According to the present invention, the support device 20 can be fixed to any type of component of the electric power transmission system 1 mentioned in this specification.

[0062] In this first embodiment of the invention, the motor cavity 5 is closed by a closed cover 10 including a fixed edge 11 and a closing wall 13. The closed cover 10 protects the electronic board 9 housed in the cavity 5. The closed cover 10 is fixed to the components of the electric power transmission system including the cavity 5 by fixing screws 8.

[0063] The fixed edge 11 of the closing cover rests on a complementary edge provided on the transmission housing. The fixed edge 11 includes a flat interface region 11a, which forms an interface with the electric powertrain. Furthermore, a seal is arranged between the two fixed edges. The closing cover ensures a seal of the powertrain in this region through the fixing screws, the compression of the seal, and the assembly of the fixed edges 11 onto the transmission housing.

[0064] The support device 20 includes a fixing region 29 for fixing to the electric powertrain, in which fixing screws 29a are accommodated. The support device 20 also includes a plate 23 connecting the various fixing regions 29 and a suspension arm 21, with a damping sleeve 3 inserted into the suspension arm 21. The damping sleeve 3 is arranged on a receiving region 22 of the support device. The receiving region 22 is perpendicular to the flat interface region 11a of the closed cover. The receiving region 22 is located at the free end of the support device furthest from the fixing edge 11.

[0065] The support device 20 includes a threaded hole 27 extending along the secondary axis X2 into the receiving area 22. A fixing screw 28 is inserted into the hole of the elastomer element 3 and screwed into the threaded hole 27 of the suspension arm 21. Reinforcing ribs connect the support device 20 to the plate 23. Other reinforcing ribs 25 of the support device extend from the inner surface 26 of the plate 23 along the direction of the fixing edge 11 of the closing cover 10.

[0066] According to the present invention, the elastomeric element 70 is located between the support device 20 and the closing cover 10. The elastomeric element 70 is supported on both the support device 20 and the closing cover 10. In this first embodiment, the elastomeric element is fixed to the support device. The damping sleeve 3 and the elastomeric element 70 are separate components.

[0067] The insertion of this elastomeric element allows for the elimination of low-frequency excitation modes associated with the molded closure. More specifically, the elastomeric element 70 is axially positioned relative to the machine axis X between the closure wall 13 (similar to the so-called "flexible" region of the closure) and the end of the reinforcing rib 25 (similar to the so-called "rigid" region of the support 20).

[0068] like Figure 1 As shown, the elastomer element 70 includes a fixed base 71 and a bearing region 72, which has an enlarged shape, given that the bearing region has a surface area greater than 1 square centimeter.

[0069] For ease of assembly, the elastomeric element 70 is held in place by means of reinforcing ribs 25. The shape of the fixing base 71 is complementary to the shape of the reinforcing ribs, which form a receiving housing for the elastomeric element. For example, the support region 72 may cover multiple reinforcing ribs.

[0070] When the support device 20 is assembled on the electric power transmission system 1, the compression of the elastomer element 70 is calculated based on the flexibility of the closing wall 13 of the closed cover.

[0071] In this first embodiment, the support device 20 covers the closed cover 10 in a geometric plane perpendicular to the machine axis X.

[0072] The axial stiffness (in N / mm) of the support device 20, measured along the machine axis X at the contact point with the elastomer element 70, is ten times greater than the stiffness of the closed cover 10, measured along the same machine axis X at the contact point with the elastomer element 70. The machine axis X is perpendicular to the contact surface of the closed cover 10.

[0073] Figure 2 The second embodiment of the present invention is illustrated schematically. The difference between the second and first embodiments is that the closed cover 10b directly supports the drive shaft and guide bearing of the reducer, and the support device 20 circumferentially covers the closed cover 10b.

[0074] In this second embodiment, the cavity 5 of the reducer 40 is closed by a cover 10b including a fixed edge 11 and a closing wall 13. The cover 10b protects the gear train housed in the cavity 5, and more specifically protects the drive shaft 41 having a rotation axis X3. The cover 10b is fixed to the components of the electric power transmission system including the cavity 5 by fixing screws 8.

[0075] The support device 20 includes a fixing region 29 for attachment to the electric power transmission system, in which a fixing screw 29a is received. The support device 20 also includes a plate 23 connecting the various fixing regions 29 and a suspension arm 21, with a damping sleeve 3 inserted into the suspension arm 21, the damping sleeve 3 being arranged on a receiving region 22 of the support device. The plate 23 of the support device includes an inner surface 26 directly facing the closing cover. The receiving region 22 is a cylindrical hole along a secondary axis X2 oriented perpendicular to the rotation axis X3, which is parallel to the machine axis X. The receiving region 22 is located at the free end of the support device furthest from the fixing edge 11.

[0076] The closing cover 10b supports the radially guiding bearing 42 in a first geometric plane P1 perpendicular to the rotation axis X3 of the bearing, and the elastomeric element 70a surrounds the closing cover 10b in a material region through which the first geometric plane P1 passes. The elastomeric element 70a specifically includes an annular portion, the inner bore 73 of which at least partially surrounds the closing cover 10b. The inner bore 73 forms the base of the elastomeric element 70a, which also includes a support region 72 formed by a series of different support surfaces. These support surfaces are, for example, angularly distributed around the rotation axis X3.

[0077] The radial guide bearing 42 is a ball bearing that supports the drive shaft 41 of the reducer. This drive shaft 41 transmits mechanical vibrations that tend to cause the closed cover to vibrate.

[0078] The closure includes a circular receiving surface that complements the annular shape of the elastomeric element 70a. These vibrations are damped by means of the elastomeric element 70a.

[0079] In this second embodiment, the second elastomeric element 70b is located between the support device 20 and the closing cover 10b. The elastomeric element 70b is fixed to the closing cover by fixing screws and is supported on the plate 23 in a rigid region that is in line with the suspension arm 21.

[0080] The second elastomeric element 70b includes a fixed base 71 and a support region 72 in the form of a point, wherein the support region has a surface area of ​​less than or equal to 1 square centimeter. The support region 72 is in direct contact with the inner surface 26 of the plate 23 of the support device.

[0081] In this example, the axial stiffness (in N / mm) of the support device 20 measured at the contact point with the elastomer element 70b is five times greater than the stiffness of the closing cover 10b measured at the contact point with the elastomer element 70b, with the measuring axis perpendicular to the contact surface of the closing cover. The measuring axis here is the rotation axis X3.

[0082] Although the invention has been described in conjunction with several specific embodiments, it is apparent that the invention is by no means limited thereto, and that the invention includes all technical equivalents of the described apparatus and combinations thereof, wherein these fall within the scope of the invention as defined in the claims.

[0083] The closure can also have other functions besides sealing a cavity formed on one of the components of the electric drive system, and can, for example, support a drive shaft or channel and guide the flow of cooling oil contained within the electric drive system.

[0084] In the claims, any reference numerals between parentheses should not be construed as limiting the claims.

Claims

1. An electric powertrain (1) for a motor vehicle, comprising: - A reversible motor (30) includes a rotor (31) capable of rotating about the machine axis (X). - Current inverter (50) that supplies power to the motor; - A speed reducer (40) which is kinematically connected to the rotor (31) of the reversible motor. - Transmission housing (45), which at least partially supports the reversible motor and / or the inverter and / or the reducer; - A closed cover (10, 10a, 10b) is attached to a cavity (5) formed on one of the elements of the electric power transmission system, the element being selected from the reversible motor, the inverter, the reducer, or the transmission housing; - A support device (20) for supporting the electric drive system, the support device (20) being designed to be fixed to the chassis of the motor vehicle and to at least partially cover the closed cover; The feature is that the elastomeric elements (70, 70a, 70b) are inserted between the support device (20) and one of the closed covers (10, 10a, 10b) of the electric drive system, while the elastomeric elements supported on the closed cover and the support device are fixed to the closed cover or fixed to the support device.

2. The electric power transmission system (1) according to claim 1, wherein, The support device (20) includes a fixed area (29) for fixing to the electric power transmission system (1), and the elastomeric elements (70, 70a, 70b) are arranged between the fixed areas (29).

3. The electric powertrain (1) according to any one of the preceding claims, wherein, The closed cover (10, 10a, 10b) includes a closed wall (13) and a fixed edge (11) supported on the electric power transmission system, and the support area (72) of the elastomeric element is arranged within the fixed edge.

4. The electric power transmission system (1) according to claim 2, wherein, The support device (20) includes a plate (23) connecting the various fixed areas (29) and a suspension arm (21), with a damping sleeve (3) inserted on the suspension arm and the damping sleeve arranged on the receiving area (22) of the support device (20).

5. The electric power transmission system (1) according to claim 4, wherein, The receiving area (22) is a cylindrical hole (22) oriented along a secondary axis (X2) perpendicular to the machine axis (X).

6. The electric powertrain (1) according to any one of the preceding claims, wherein, The elastomeric element (70) includes a fixed base (71) and at least one support region (72), which is either a point or an enlarged area or formed by a series of different support surfaces.

7. The electric power transmission system (1) according to any one of claims 4 to 6, wherein, The plate (23) is reinforced by reinforcing ribs (25), and the elastomeric element (70) is held in place by the reinforcing ribs (25).

8. The electric power transmission system (1) according to claim 7, wherein, The elastomeric element (70) is supported on the plate (23) in a rigid region that is linearly positioned with respect to the suspension arm (21).

9. The electric powertrain (1) according to claim 8, comprising at least one reinforcing rib (25) connecting the suspension arm (21) to the plate (23).

10. The electric power transmission system (1) according to any one of claims 4 to 9, wherein, The fixing screw (28) is inserted into the hole of the damping sleeve (3) and screwed into the threaded hole of the suspension arm (21).

11. The electric power transmission system (1) according to any one of claims 4 to 10, wherein, The plate (23) of the support device (20) includes an inner surface (26) arranged facing the cavity (5).

12. The electric power transmission system (1) according to claim 7, wherein, The reinforcing rib (25) extends from the inner surface (26) of the plate (23) along the direction of the closing cover (10).

13. The electric powertrain (1) according to any one of the preceding claims, wherein, The elastomeric element (70a) includes an annular portion, the inner hole (73) of which at least partially surrounds the closure cap.

14. The electric powertrain (1) according to any one of the preceding claims, wherein, The closing cover (10b) closes the cavity (5) of the reducer or the transmission housing and supports the radial guide bearing (42) in a first geometric plane (P1) perpendicular to the axis of rotation (X3) of the radial guide bearing, the elastomeric element (70) surrounding the closing cover in the material region through which the first geometric plane (P1) passes.

15. The electric power transmission system (1) according to claim 14, wherein, The radial guide bearing (42) supports the drive shaft (41) of the reducer (40) or the rotor (31) of the reversible motor (30).

16. The electric powertrain (1) according to any one of the preceding claims, wherein, The axial stiffness of the support device (20) measured in N / mm at the contact point with the elastomer elements (70, 70a, 70b) is at least five times the stiffness of the closing cover (10, 10a, 10b) measured at the contact point with the elastomer elements, with the measurement axis perpendicular to the contact surface of the closing cover.

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