Closing cover for an electric powertrain and electric powertrain including a closing cover.

Abstract

The invention relates to a closing cover (10) for an electric powertrain (1), arranged to close a housing of the electric powertrain, the closing cover being formed by a first wall (11) and a second wall (12), the two walls (11, 12) being decoupled. Figure for the abstract: Fig. 2.

Description

Title of the invention: Closing cover for an electric powertrain and electric powertrain comprising a closing cover.

[0001] The invention relates to the field of electric powertrains for motor vehicles and more particularly to the closing cover of this powertrain. 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] Vibrations, due for example to connections and disconnections within the gearbox and reversible electric machine assembly, particularly at the external surfaces, can propagate noise into and / or out of the motor vehicle, for example a passenger car or an industrial vehicle. For example, when a transmission housing cover exhibits vibrational 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 positioned, in particular, between the electric motor housing and the vehicle chassis. The suspension mounts are generally located on the most rigid parts of the housing. However, they are only effective against vibrations within a limited frequency range. Furthermore, the available space around the powertrain is limited, making the installation of this type of suspension mount difficult.

[0004] An electric powertrain as described in German patent application DE 102021214776 A1 comprises a reversible electric machine and a speed reducer integrated within a transmission housing. To control the electric machine, an inverter incorporates electronic components that manage the electrical power according to the vehicle's needs. The inverter's electronic components are supported by the transmission housing and protected by a cover attached to the transmission housing. A drawback of this type of powertrain stems from the fact that the cover has, in particular, a rigid mounting frame and a thin wall that can vibrate due to its natural frequency. The noise generated by the vibrations of the electric machine and the speed reducer is then transmitted through the surface of the cover.

[0005] The present invention therefore aims to overcome one or more of the drawbacks of prior art devices by proposing an improved cover for a powertrain.

[0006] For this purpose the present invention proposes a closing cover for an electric powertrain, arranged to close a housing of the electric powertrain, the closing cover being formed by a first wall and a second wall, the two walls being decoupled.

[0007] Such a double-wall configuration makes it possible to obtain a reduction in transmitted noise.

[0008] According to one embodiment of the invention, the second wall is disposed at a distance from the first wall.

[0009] According to one embodiment of the invention, the distance is defined so that the sum of the distance and the thickness of the second wall is less than or equal to 6mm.

[0010] According to one embodiment of the invention, the second wall is arranged opposite the first wall.

[0011] According to one embodiment of the invention, the second wall is arranged parallel to the first wall.

[0012] According to one embodiment of the invention, the second wall is fixed to the first wall.

[0013] According to one embodiment of the invention, the space between the two walls is filled with air.

[0014] According to one embodiment of the invention, the space between the two walls is filled with a sound-absorbing material, and for example resin, statcoil or any other equivalent material.

[0015] The invention also relates to an electric powertrain comprising a closing hood according to the invention.

[0016] According to one embodiment of the invention, a housing of an inverter is closed by the closing cover.

[0017] Other objects, features and advantages of the invention will be better understood and will become more apparent upon reading the description given below, with reference to the accompanying figures, given by way of example and in which:

[0018] - [Fig. 1] is an elevation view of an example of a powertrain including a closing cover according to an embodiment of the invention,

[0019] - [Fig. 2] is a schematic representation of a cross-sectional view of part of a powertrain comprising a closing hood according to an embodiment of the invention.

[0020] Figure 1 schematically illustrates an electric powertrain 1 for a motor vehicle according to the invention, comprising a reversible electric machine 30 including a stator (not shown), a rotor 31 rotating about a machine axis X, an electric current inverter 50 supplying the electric machine, and a speed reducer 40 kinematically linked to the rotor of the reversible electric machine. The inverter 50 is housed in a compartment at one end of the powertrain. The output shaft of the speed reducer drives one or more drive wheels of the motor vehicle, in this case a motor vehicle.

[0021] The speed reducer 40 housed inside the transmission casing comprises transmission shafts to which gears are rotationally attached, enabling a speed reduction ratio between the rotor of the electric machine and the output shaft of the speed reducer. The speed reducer itself is protected from the external environment by a closing cover.

[0022] In the context of the invention, a hood 10 with a double wall 11, 12 is used to limit transmitted noise. For this purpose, a second wall 12 is arranged at the level of the assembly concerned, and comprising a first wall 11 closing a housing or casing, for the limitation of noise.

[0023] In the context of the invention, the second wall 12 is decoupled from the first wall 11.

[0024] According to one embodiment of the invention, the second wall is made of a material with a higher density than the density of the first wall to optimize noise limitation.

[0025] According to one embodiment of the invention, the first wall is made of aluminium, density of 2,700 kg / m3 and critical frequency of 1300Hz for 1 cm, and the second wall is made of steel, density of 7,800 kg / m3 and critical frequency of 1000Hz for 1 cm.

[0026] The invention is illustrated with an embodiment shown [Fig. 1]. The parameters of this embodiment are applicable to all embodiments covered by the invention.

[0027] According to one embodiment of the invention, the cavity of the powertrain housing 1 is closed by a closing cover 10 which forms a first wall 11.

[0028] According to one embodiment of the invention, it is the housing 51 of the inverter 50 which is closed by a cover 10, forming a first wall 11.

[0029] In the context of the invention, the lid 10 formed by a first wall 11 is doubled by a second wall 12.

[0030] According to one embodiment of the invention, the second wall 12 is arranged opposite the first wall 11.

[0031] According to one embodiment of the invention, the second wall 12 is arranged parallel to the first wall 11.

[0032] According to one embodiment of the invention, the second wall 12 is fixed to the first wall 11.

[0033] In the context of the invention, the second wall 12 is disposed at a distance d from the first wall 11, the first wall 11 has a thickness e1 and the second wall 12 has a thickness e2.

[0034] The input data are therefore:

[0035] - the distance d between the 2 walls

[0036] - the thickness of each wall el, e2 giving the surface mass of each wall ml and m2 and the critical frequencies Fl, F2 giving Fcml and Fcm2

[0037] - the resonance frequency Fr

[0038] -Fcml=el / Fl

[0039] - Fcm2 = e2 / F2

[0040] According to one embodiment of the invention,

[0041] - the maximum added thickness is 6mm

[0042] - Fcml / Fcm2>2, to avoid a cumulative effect on the filtering

[0043] - Fr<700 Hz

[0044] - The ratio between the resonance frequency of the second wall is 2 times the resonance frequency of the first to avoid a weakness in the filtering effect.

[0045] It is therefore possible to define 3 criteria to determine the thickness of the second wall and the distance between the two walls.

[0046] Criterion 1: d+e2 < 6mm

[0047] Criterion 2: e2 < 0.5x(elxF2) / Fl

[0048] Criterion 3: d>0.0144*[1000 / (el* pl)+1000 / (el*pl)]*1000 (mm)

[0049] A configuration of the invention is implemented according to these criteria (Table 1): Wall 1 Wall 2 Material aluminum steel F (Hz) 1300 1000 p (Kg / m3) 2700 7800 e (mm) 3 1.2

[0050] Table 1

[0051] And d = 4 mm.

[0052] Such a double-wall configuration makes it possible to obtain a reduction in transmitted noise.

[0053] According to one embodiment of the invention, the space between the two walls 11,12 is filled with air.

[0054] According to one embodiment of the invention, the space between the two walls 11,12 is filled with a sound-absorbing material, and for example resin, statcoil or any other equivalent material.

[0055] The scope of the present invention is not limited to the details given above and allows for embodiments in many other specific forms without departing from the field of application of the invention. Therefore, the present embodiments should be considered by way of illustration and may be modified without, however, departing from the scope defined by the claims.

Claims

Demands

1. Closing cover (10) for an electric powertrain (1), arranged to close a housing of the electric powertrain, the closing cover being formed by a first wall (11) and a second wall (12), the two walls (11, 12) being decoupled.

2. Closing cover (10) according to claim 1, in which the second wall (12) is disposed at a distance (d) from the first wall (11).

3. Closing cover (10) according to claim 2, wherein the distance (d) is defined such that the sum of the distance (d) and the thickness (e2) of the second wall (12) is less than or equal to 6mm.

4. Closing cover (10) according to any one of claims 1 to 3, wherein the second wall (12) is arranged opposite the first wall (11).

5. Closing cover (10) according to any one of claims 1 to 4, wherein the second wall (12) is arranged parallel to the first wall (11).

6. Closing cover (10) according to any one of claims 1 to 5, wherein the second wall (12) is fixed to the first wall (11).

7. Closing cover (10) according to any one of claims 1 to 6, in which a space between the two walls (11, 12) is filled with air.

8. Closing cover (10) according to any one of claims 1 to 6, wherein a space between the two walls (11, 12) is filled with a sound-absorbing material.

9. Electric powertrain (1) comprising a closing cover (10) according to any one of claims 1 to 8.

10. Electric powertrain (1) according to claim 9, wherein a housing (51) of an inverter (50) is closed by the closing cover (10).

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