CN110945750A

CN110945750A - Rotating electrical machine comprising an elastic component

Info

Publication number: CN110945750A
Application number: CN201880048960.1A
Authority: CN
Inventors: M.雷东; P.法韦罗尔; A.索维格内特; M.格罗斯佩奥德
Original assignee: Valeo Equipements Electriques Moteur SAS
Current assignee: Valeo Equipements Electriques Moteur SAS
Priority date: 2017-07-27
Filing date: 2018-07-26
Publication date: 2020-03-31
Also published as: FR3069724B1; FR3069724A1; WO2019020730A1; EP3659238A1

Abstract

The invention mainly relates to an elastic component (40) for a rotary electric machine (10) comprising a stator (15) carried by a casing (11). An elastic member (40) is assembled between the stator (15) and the housing (11) in the radial direction, is formed at least partially of a metal material, and is shaped to have rigidity in the radial direction for filtering vibration of the stator (15).

Description

Rotating electrical machine comprising an elastic component

Technical Field

The present invention relates to an elastic member for equipping a rotating electrical machine of a motor vehicle, and to a rotating electrical machine comprising an elastic member of this type.

Background

Motor vehicles with a heat engine are equipped with an alternator, the purpose of which is to convert the mechanical energy obtained from the engine into electrical energy, in particular to recharge the batteries of the vehicle and to supply the onboard electrical network. To this end, the alternator includes a rotor mounted on a rotating shaft and a stator surrounding the rotor, the stator being supported by a housing.

When the alternator is operated, the rotor generates a rotating magnetic field that acts on and vibrates the stator. Depending on the rotational speed of the alternator, the vibration of the stator may generate magnetic noise in the form of squeal, causing audible discomfort.

In order to damp magnetic noise, it is known, in particular from document EP 1249064B 1, to insert, for example, a damper and a resin between the stator and the housing element for damping vibrations. A disadvantage of this procedure is that a considerable amount of time is required to put a damping element of this type in place. In practice, in particular, it is necessary to place a buffer, pour the resin and then wait for it to polymerize.

Disclosure of Invention

The object of the present invention is to solve the above problems by proposing a device for damping the vibrations of a rotating electric machine, said device being mounted more quickly.

To this end, a first aspect of the invention relates to a rotating electrical machine for a motor vehicle. The rotating electric machine includes: a stator; a housing surrounding a rotor and a stator, the rotor rotating about an axis; an elastic member disposed between the stator and the housing in the radial direction, the elastic member being made at least partially of a metal material and formed to have rigidity in the radial direction, the rigidity being designed to filter vibration of the stator.

The elastic member is a mechanical member placed between the stator and the housing of the rotary electric machine. Thus, the speed of placing the unit in place is fast and does not require any waiting time, contrary to the case of resins used in the prior art.

According to one embodiment, the resilient member is made of a multi-layer material. By "multilayer material" is meant that the elastic member is made of a series of layers of different materials, which are connected to each other in the radial direction.

For example, the resilient member is made of at least two different materials.

For example, the resilient member is made of three different materials.

For example, the elastic member is made of a series of layers of different materials having different properties.

For example, at least two layers have different radial stiffness.

For example, at least one layer is made of metal.

For example, at least one layer is made of an organic compound.

For example, a layer made of an organic compound has a higher damping modulus than a layer made of a metal material.

For example, a layer of damping material is included between two layers of metal material.

The elastic means thus make it possible to both filter and damp the vibrations of the stator in the radial direction.

For example, the resilient member extends circumferentially around the stator.

According to one embodiment, the resilient member has a plane of symmetry, said plane of symmetry comprising the axis of rotation. In addition, the elastic element may also have a second plane of symmetry extending perpendicular to the axis of rotation.

According to one embodiment, the resilient member has a cross-section relative to the axis, said cross-section being open. In this case, the first plane of symmetry passes through the opening in the circumferential direction of the opening, in particular through the center.

According to one embodiment, the resilient member forms a circular arc having an angle of at least 240 °.

According to one embodiment, the resilient member has an undulating shape. Undulations are generated between the housing and the stator in the positioning direction of the unit. The undulations may therefore be radial if the resilient member is positioned radially between the housing and the stator. As a variant, the relief may be axial if the elastic member is positioned axially between the housing and the stator.

According to one embodiment, the resilient member comprises a boss. The projection extends in particular in the radial direction.

According to one embodiment, the resilient member comprises an inner surface oriented towards the reference axis and an outer surface opposite the inner surface, said outer and/or inner surface being provided with a boss.

According to one embodiment, the height of each boss in the radial direction is preferably comprised between 0.5mm and 30 mm.

According to one embodiment, each boss comprises an axially extending support surface.

According to one embodiment, the resilient member comprises at least one opening, which is arranged adjacent to one of the bosses. In this case, the elastic member includes openings provided on both sides of at least one boss.

For example, the opening extends in the axial direction. As a variant, the opening extends in the circumferential direction.

According to one embodiment, the resilient member comprises at least one opening in the boss.

According to one embodiment, the resilient member comprises an opening created to divide the boss into two parts, preferably having the same dimensions.

According to one embodiment, the thickness of the elastic means in the radial direction is comprised between 0.1mm and 1 mm.

According to one embodiment, the stator comprises a body extending axially along a first length, wherein the elastic means extend axially along a second length comprised between 10% and 120% of the first length.

According to one embodiment, the electric machine comprises a second elastic member extending in the axial direction between the stator and the housing and formed to have a stiffness in the axial direction, said stiffness being designed to filter vibrations of the stator. The second elastic member may be used as a complement to the first elastic member in order to dampen the transmission of vibrations in the second direction, in particular the axial direction.

According to one embodiment, the housing comprises a first bearing, called "front bearing", and a second bearing, called "rear bearing", wherein the elastic member mechanically connects the stator to the front bearing, and the front bearing corresponds to the bearing closer to the drive unit of the rotating electrical machine.

Drawings

The invention, together with its various applications, may be best understood by referring to the following description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic longitudinal cross-sectional view of an alternator according to an embodiment of the present invention;

fig. 2 is a schematic perspective view of a first example of an elastic member equipped with the alternator of fig. 1;

FIG. 3 is an enlarged view of the boss of the elastomeric component of FIG. 2;

FIG. 4A shows a first variant embodiment of the boss in FIG. 3;

FIG. 4B shows a second variant embodiment of the boss in FIG. 3;

FIG. 5 shows a third variant embodiment of the boss in FIG. 3;

FIG. 6 is a schematic perspective view of a second example of a resilient member equipped with the alternator of FIG. 1;

figures 7A and 7B show the variation curves of the magnetic noise of the alternator of figure 1 and of an alternator according to the prior art, respectively, depending on the rotation speed of the alternator, with and without, respectively, the preheating phase of the alternator;

fig. 8 is a perspective view of a third example of the elastic member according to the present invention.

These drawings are provided by way of indication only and in no way limit the invention.

For purposes of clarity, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

Detailed Description

Motor vehicles with a heat engine are equipped with a rotating electric machine, such as an alternator or an alternator-starter, which is configured to convert the mechanical energy obtained from the heat engine into electrical energy, in particular to recharge the batteries of the vehicle and to supply the onboard electrical network.

The alternator-starter is a reversible alternator, i.e. it also has an operating mode in which it converts electrical energy into mechanical energy in order to start, in particular, a heat engine of the motor vehicle. In this case, the rotary machine functions as an electric motor.

An embodiment of an alternator 10 according to the present invention will now be described with reference to fig. 1. The alternator 10 includes a rotor 12 integrally rotatably fitted on a shaft 13 and a stator 15 surrounding the rotor 12. The rotor 12 and the stator 15 are arranged inside a housing 11 comprising a front bearing 16 and a rear bearing 17.

The shaft 13 extends along a longitudinal axis and is rotated by a motor via a motion transmitting device comprising a pulley 20, which is fixed at the front end of the shaft 13. The longitudinal axis X of the shaft 13 forms the axis of rotation of the shaft 13.

In all the description and claims, the terms "axial", "radial", "tangential", "inner", "outer" and derivatives thereof are defined with respect to the longitudinal axis X.

The stator 15 includes a main body 27 formed by a stack of metal plates, each having a substantially annular shape. A notch is provided at an inner periphery of each metal plate. The notches in the stacked metal plates form grooves in which the conductive wire is wound to form the armature winding 28. The coils 28 define an electrical phase, each phase including at least one coil. Core 28 forms bun 29 and bun 30 disposed on both sides of main body 27 of stator 15.

The main body 27 of the stator 15 has a substantially annular cylindrical shape, which is delimited by a front surface arranged facing the front bearing 16, a rear surface arranged facing the rear bearing 17, an inner cylindrical surface and an outer cylindrical surface. The front and rear surfaces of the main body 27 of the stator 15 are transverse with respect to the longitudinal axis X.

The rotor 12 comprises two magnet wheels 31, each comprising a flange 32 disposed transversely with respect to the longitudinal axis X, on the periphery of which an axially extending claw 33 is disposed. The claws 33 of one magnet wheel 31 are angularly offset with respect to the claws 33 of the other magnet wheel 31 so that the claws 43 of the two magnet wheels 31 alternately interpenetrate. A cylindrical core 34 is axially inserted between the flanges 32 of the magnet wheel 31. In this case, the core 34 is made up of two half-cores, each of which belongs to one of the flanges 32. The core 34 supports at its outer periphery an excitation coil 35 wound in an insulator located radially between the core 34 and the excitation coil 35.

The

bearings

16, 17 are equipped with

ball bearings

18, 19, respectively, for rotatably mounting the shaft 13. The rear bearing 17 is equipped with a brush holder 24 provided with brushes 23 designed to rub on slip rings 21 electrically connected to the excitation coils 35 of the rotor 12. The excitation coil 35 may thus be powered by an excitation current obtained from a potentiostat. A slip ring 21 is provided on the rear end of the shaft 13.

Cooling of the alternator 10 is ensured by circulation of air generated by two fans 25, 26 respectively provided on the front and rear surfaces of the rotor 12.

The alternator 10 includes an elastic member 40 disposed between the stator 15 and the housing 11. According to the embodiment in fig. 1, an elastic member 40 is provided between the stator 15 and the single bearing (in this case the front bearing 16) in order to facilitate assembly. According to other embodiments, the elastic member may mechanically connect the stator to the rear bearing or to both bearings at once. The elastic member 40 is formed to filter vibrations of the stator 15 caused by electromagnetic force existing in the alternator 10 when the alternator is operated. Therefore, the elastic member 40 restricts the propagation of the vibration of the stator 15 toward the housing 11 of the alternator 10, thereby reducing the magnetic noise of the alternator 10.

The resilient member 40 is, for example, in the shape of a tolerance ring, as shown in fig. 2. In this case, the elastic member 40 is fitted around the outer cylindrical surface of the body 27 of the stator 15. The elastic member 40 includes: an inner surface 41 arranged to face and preferably contact an outer cylindrical surface of the body 27 of the stator 15; an outer surface 42 opposite the inner surface 41.

According to this embodiment, the resilient member 40 includes a boss 44 extending radially on the outside of the outer surface 42. Instead, the inner surface 41 is provided with a recess 45 having a shape complementary to the boss 44. The boss 44 serves as a damping element between the stator 15 and the housing 11. The boss 44 of the resilient member 40 can be better seen in fig. 3.

According to another embodiment, the bosses may be inverted, i.e. they may be provided on the inner circumferential surface 41.

When assembling the stator 15 in the housing 11, the boss 44 of the elastic member 40 is at least partially elastically deformed so as to exert a radial force on the stator 15 and the housing 11 to prevent axial and/or radial and/or rotational displacement of the stator 15 relative to the housing 11. The bosses 44 of the elastic member 40 thus make it possible to hold the stator 15 in position in the housing 11.

The elastic member 40 extends along a total length LT preferably comprised between 10% and 120% of the length LS of the main body 27 of the stator 15. Thus, the elastic member may extend along an axial length that is shorter than an axial length of the stator body. Or, as a variant, it may extend along a length longer than the length of the stator body. The elastic means 40 have a thickness E in the radial direction, preferably comprised between 0.1mm and 1 mm.

Each boss 44 includes a support surface 47 which is provided in contact with the housing 11 if the boss is provided on the outer peripheral surface of the elastic member, and with the main body 27 of the stator if the boss is arranged on the inner peripheral surface of the unit. According to a variant embodiment, the elastic means may comprise bosses on the inner and outer surfaces of the unit, respectively. The arrangement of the bosses on one or the other surface may depend on the assembly method of the alternator, in the sense that the support surface 47 is in contact in particular with the moving part (housing or stator) during the installation of the stator in the housing. Thus, in particular prior to assembly between the stator and the housing, the elastic member is mounted on a part that is not movable during this assembly.

The support surface 47 of each boss 44 extends axially along a length L preferably comprised between 20% and 110% of the length LS of the main body 27 of the stator 15. Each boss 44 has a height H considered in the radial direction between the inner surface 41 and the support surface 27, preferably comprised between 0.5mm and 30 mm. In addition, each boss 44 has a width, for example in the circumferential direction, preferably comprised between 0.2mm and 30 mm.

For example, the bosses of a single resilient member 40 are all the same around the circumference of the unit. As another example, the bosses may be regularly distributed around the circumference of the elastomeric member, or irregularly distributed. For example, groups of a plurality of bosses may be regularly distributed with each other, and in this case, in the drawings, groups of two bosses are shown.

The elastic member 40 has a cross section with respect to the axis X, which is open. In other words, the resilient member 40 is not a closed loop. Preferably, the elastic member 40 is such that it covers an angle of at least 240 °, which makes it possible to ensure the centering of the stator 15 with respect to the housing 11.

The elastic member 40 may be made of metal such as steel or aluminum. The advantage of using metal is that a good heat conduction is obtained between the stator 15 and the housing 11, thereby dissipating the heat caused by the generation of the current induced in the stator.

According to a variant embodiment, the elastic means 40 may comprise openings 48 provided on both sides of each boss 44. As a variant, the elastic means 40 may comprise a single opening for each boss 44, for example arranged in the middle of the boss. According to another variant, the boss 44 may be formed by a plurality of strips spaced apart by openings.

The opening 48 may extend axially as shown in fig. 4A or tangentially as shown in fig. 5. Optionally, each boss 44 may include an additional opening 48, as shown in FIG. 4B, created to divide the boss 44 into two portions, which preferably have the same dimensions. The different openings comprised by the resilient member 40 and their dimensions are designed to adjust the stiffness of the boss 44, in particular in the radial direction, such that the resilient member 40 is sufficiently rigid to hold the stator 15 in place in the housing 11, while being sufficiently flexible to filter vibrations.

According to a variant embodiment, the elastic means 40 can be made of a multilayer material 60. By "multilayer material" is meant that the elastic member is made of a series of layers of different materials, which are connected to each other in the radial direction. In the example shown in fig. 6, the elastic member includes the boss 44, and is made of three

layers

61, 62, 61. The upper and lower layers 61 are made of a metal material, and the intermediate layer 62 is made of an organic compound.

The metal layer may be made of steel, aluminum, copper, brass or other materials. The intermediate layer may be made of rubber, polymer foam, or other material.

The intermediate layer made of an organic compound has a higher damping modulus than the two layers made of a metallic material. The elastic means thus make it possible to both filter and damp the vibrations of the stator in the radial direction.

Fig. 7A shows a first curve 601 of the variation of the magnetic noise BM according to the rotation speed V of the alternator according to the prior art, and a second curve 602 of the variation of the magnetic noise BM according to the rotation speed V of the alternator 10 according to the invention. These two

curves

601, 602 are obtained at ambient temperature of about 25 ℃, the alternator being put into operation when it is cold, i.e. the alternator has not undergone a warm-up phase before performing the measurement.

In all figures, the magnetic noise BM is expressed in acoustic decibels db (a) w and the rotation speed is expressed in revolutions per minute rpm.

The reduction in the magnetic noise BM is found at least in the speed range comprised between 1800rpm and 5200 rpm. A speed range comprised between 1800rpm and 4000rpm is particularly advantageous, since in this range the magnetic noise is most easily audible and therefore produces the greatest discomfort. Indeed, outside this range, the magnetic noise is masked by the air noise of the fan that ensures the cooling of the alternator.

In a manner similar to fig. 7A, fig. 7B shows a third curve 603 of the variation of the magnetic noise BM according to the rotation speed V of the alternator according to the prior art, and a second curve 604 of the variation of the magnetic noise BM according to the rotation speed V of the alternator 10 according to the present invention. On the other hand, these two

curves

603, 604 are obtained when the alternator has undergone a warm-up phase and at an ambient temperature of about 25 ℃. It was also found that in the speed range V comprised between 1800rpm and 4000rpm, the magnetic noise is reduced or remains approximately equal.

Fig. 8 shows another example of the second elastic member 50, which may be installed in the alternator 10 in addition to the elastic member 40.

The elastic member 50 has, for example, a toroidal shape extending around the axis of revolution, and is preferably made of metal. Elastic members of this type can be assembled axially between each face of the body 27 of the stator 15 and the

respective bearing

16, 17, so that the axis of revolution coincides with the axis of rotation X. Therefore, the alternator 10 may include two second elastic members 50.

The elastic member 50 has undulations in the axial direction that serve as damping elements. The elastic member 50 has a cross section transverse to the axis of revolution, said cross section being open.

It will be understood that the invention is not limited to the embodiments described with reference to the drawings, and that modifications may be envisaged without departing from the context of the invention.

Claims

1. A rotating electric machine for motor vehicles, the electric machine (10) comprising:

a stator (15);

a housing (11) surrounding a rotor and the stator, the rotor rotating about an axis (X); and

an elastic member (40) disposed between the stator (15) and the housing (11) in a radial direction;

the electric machine is characterized in that the elastic part (40) is at least partially made of a metal material and it is formed with a stiffness in the radial direction designed to filter the vibrations of the stator.

2. The machine according to claim 1, characterized in that said elastic member (40) has a plane of symmetry comprising said axis (X).

3. The machine according to claim 1 or 2, characterized in that said elastic member (40) has a cross section with respect to said axis (X), said cross section being open.

4. A machine as claimed in any one of claims 1 to 3, characterized in that said elastic member (40) forms an arc of a circle having an angle of at least 240 °.

5. The machine according to any of claims 1 to 4, characterized in that the elastic member (40) has an undulating shape.

6. The machine according to any of claims 1 to 5, characterized in that the elastic member (40) comprises a boss (44).

7. An electric machine according to claim 6, characterized in that the elastic member (40) comprises an inner surface (41) oriented towards the axis (X) and an outer surface (42) opposite the inner surface (41), wherein the outer surface (42) is provided with the boss (44).

8. The machine according to claim 6 or 7, characterized in that the elastic member (40) comprises an inner surface (41) oriented towards the axis (X) and an outer surface (42) opposite the inner surface (41), wherein the inner surface (41) is provided with the boss (44).

9. An electric machine according to any of claims 6-8, characterized in that each boss (44) comprises an axially extending support surface (47).

10. The machine according to any of claims 6 to 9, characterized in that the elastic member (40) comprises at least one opening (48) arranged adjacent to one of the bosses (44).

11. The electric machine according to claim 10, characterized in that the elastic member (40) comprises openings (48) provided on both sides of at least one boss (44).

12. An electric machine according to claim 10 or 11, characterized in that the opening (48) extends in an axial direction.

13. An electric machine according to claim 10 or 11, characterized in that the openings (48) extend in a circumferential direction.

14. The machine according to any of claims 1 to 13, characterized in that it comprises a second elastic member (50) extending in the axial direction between the stator (15) and the housing (11) and formed to have a stiffness in the axial direction designed to filter the vibrations of the stator.