WO2019110410A1

WO2019110410A1 - Electric motor

Info

Publication number: WO2019110410A1
Application number: PCT/EP2018/082970
Authority: WO
Inventors: Lakshmi Narayanan MUTHU; Uwe Roessler
Original assignee: Robert Bosch Gmbh
Priority date: 2017-12-08
Filing date: 2018-11-29
Publication date: 2019-06-13
Also published as: DE102017222281A1

Abstract

The invention relates to an electric motor (10), in particular an external rotor motor, having a rotor (14), a stator (12) and a motor shaft (26), wherein the motor shaft (26) is associated with the stator (12) or the rotor (14) and has an axis of rotation (32), the rotor (14) and stator (12) being mounted by means of at least one rolling bearing (40, 42), which has at least one end face (60), in such a way that they can rotate relative to each other about said axis of rotation, and wherein the motor shaft (26) has a lateral surface (27) and a contacting element (48) is arranged between the rotor (14) and the stator (12), said contacting element being in contact with the at least one rolling bearing (40, 42) and abutting the lateral surface (27) of the motor shaft (26) and/or the end face (60) of the rolling element bearing (40, 42) in such a way that it is movable, in particular rotatable, relative thereto. It is proposed that the contacting element (48) is formed at least in part from an electrically conductive nonwoven material (52).

Description

title

electric motor

The invention relates to an electric motor according to the preamble of the independent claim.

State of the art

Electromechanical commutation of motors produces electromagnetic waves that are emitted into the environment. These occurring electromagnetic waves should be reduced.

From DE 10 2012 201 545 Al a device for shielding electromagnetic interference of an electric motor is known, which means

a clocked signal is driven. It is envisaged that the rotor with

the motor shaft is connected via an electrically conductive connecting element,

wherein the connecting element acts on the end face of the motor shaft and on

the end face of the rotor component is attached.

Disclosure of the Invention Advantages of the Invention

The invention relates to an electric motor, in particular an external rotor motor, with a rotor, a stator and a motor shaft, wherein the motor shaft is associated with the stator or the rotor and a Has axis of rotation about which rotor and stator to each other by means of at least one rolling bearing, which has at least one end face, are rotatably mounted, and wherein the motor shaft a

Has lateral surface and between the rotor and a stator

Contacting element is arranged, which is in contact with the at least one roller bearing and on the lateral surface of the motor shaft and, alternatively or additionally, the end face of the rolling bearing to this movable, in particular rotatably applied. It is proposed that the contacting element is at least partially formed from an electrically conductive nonwoven fabric.

The electric motor according to the invention with the features of

independent

Claim has the advantage that the contacting element can be installed in a particularly space-saving and easy. By using a Kontaktierlementes, which is at least partially formed of an electrically conductive nonwoven fabric, also undesirable squeaking noise can be further minimized in an advantageous manner. It is also to be regarded as particularly advantageous that the nonwoven fabric according to the invention is optimized with respect to its sliding properties and at the same time has good electrical conductivity. Even with a radial

Contacting of rotating components can be minimized by a trained contacting element now advantageously the friction and at the same time a stable ohmic

Compound be provided to compensate for potential differences between the rotor and stator. Such minimization of friction also has an advantageous effect on the heat development and the wear of such a contacting element. In addition, the contact element according to the invention can be integrated into existing systems due to its small size without additional adjustments of the electric motor or even retrofitted. The term "nonwoven" may in the present case a

Be understood, which consists entirely or substantially of fibers, these fibers both

Spun fibers or filaments and / or fibers with a degree of slimming, that is with a ratio of fiber length in mm to

Fiber diameter in mm, of at least 300 can be. Further, it is conceivable that the fibers are interconnected in the nonwoven fabric by entanglement and / or cohesion and / or adhesion, wherein the character-determining fibers can be oriented in the nonwoven fabric and / or arranged confused. Moreover, it is also conceivable that the fibers are oriented in such a way that they form a brush-like structure.

In the context of the present invention, an imaginary one can be imagined under a rotation axis

Axis, to which a body, in particular the rotor, in the

Rotates sense of a rotation axis. In contrast to the rotation axis, which one

purely imaginary axis can, in relation to the present

Invention under

the term motor shaft understood an objective machine element

become.

Furthermore, in the context of the present invention under a

Face of the

Rolling the surface of the rolling bearing are understood, which extends in a plane perpendicular or substantially perpendicular to the axis of rotation of the motor shaft. In other words the End face limits the rolling bearing axially along the axis of rotation. The term end face is not limited to a flat surface, but the end face can be any

Have surface contour.

In the context of the present invention, moreover, under a

Outer surface of the motor shaft that surface of the motor shaft are understood, which extends circumferentially in the axial direction, that is, in the direction of the axis of rotation. The term lateral surface is not limited to a cylindrical surface, but the

Jacket surface projections and recesses include.

According to the invention, the rotor and stator are connected to one another by means of at least one

Bearings rotatably mounted. For this purpose, for example, the motor shaft in

Motor support or stator be firmly clamped, so that the rotor in operation to the

Motor shaft rotates. However, it is also conceivable that the motor shaft itself in the rotor

is clamped and is rotatably mounted together with the rotor in the stator or engine block.

Preferably, the electric motor is designed such that the contacting element is stationary, that is not co-rotated during operation of the electric motor. In this way, the nonwoven fabric is exposed to lower shear loads. According to another preferred

Embodiment of the invention, the electric motor is designed as an external rotor motor. In such an embodiment, the shielding effect of the rotor itself can be used to improve the electromagnetic compatibility in an advantageous manner. The measures listed in the dependent claims, advantageous refinements and improvements in the

independent

Claims given characteristics.

According to an advantageous embodiment of the invention, it is provided that the contacting is rotatably connected to the at least one rolling bearing. In this context, the term "rotationally fixed" is also to be understood that the smallest relative movements between the contacting element and the rolling bearing can occur in the region of the rotationally fixed connection. Especially with a

Starting the electric motor, it may therefore be that such minimum relative movements occur between the contacting and the rolling bearing on the non-rotatable connection.

Preferably, the rolling bearing has an inner ring and an outer ring, wherein the contacting element is rotatably connected to the outer ring and movable on the inner ring, in particular rotatably. By the electric

Bridging between the inner ring and the outer ring, the overarching distance can be kept low in an advantageous manner. Although such bearings have a plurality of electrically conductive

Components on which are basically suitable

To compensate for potential differences, due to the lubrication of the bearings, however, these are not a complete electrical line safely comply, creating a combination of such

Rolling with a contact element according to the invention for

Compensating potential differences proves to be particularly advantageous. Furthermore, such a contact element is low

Relative speeds, which is beneficial to the burden of Kontaktierelementes and concomitantly affects its life.

According to advantageous embodiment of the invention that is the

Kontaktierelement with the electrically conductive nonwoven fabric on the

End face of the inner ring of the rolling bearing and additionally or alternatively on the lateral surface of the motor shaft grinding.

In this context, analogous to the end face of the rolling bearing under the end face of the inner ring of the rolling bearing that surface of the rolling bearing can be understood, which in a plane perpendicular or substantially perpendicular to the axis of rotation of the

Motor shaft extends. Such a grinding contact via the electrically conductive nonwoven fabric has the advantage that the frictional force and concomitantly the wear of the contacting element can be minimized.

According to an advantageous embodiment of the invention, the electrically conductive nonwoven material abrades both on the end face of the inner ring of the rolling bearing and on the lateral surface of the motor shaft. Such an embodiment has the advantage that in case of loss of contact with one of the two sliding contact surfaces of the

Potential equalization can be done via the corresponding second sliding contact surface. In particular, a slight lifting of the

Kontaktierelementes of the end face of the inner ring of the bearing can during operation by start-up movements of the electric motor or

Schüttei loads occur so that the function of the compensation of the potential differences can be maintained over the corresponding second sliding contact surface in an advantageous manner. Such a multi-sided sliding contact thus advantageously makes it possible to increase the reliability of the equipotential bonding. In an advantageous embodiment, the motor shaft is rotationally fixed in the stator

attached, the inner ring rotatably connected to the motor shaft and the outer ring

abuts a bearing seat, wherein the bearing seat is formed on the rotor.

According to a particularly advantageous embodiment of the invention, it is provided that the contacting element is integrally formed from an electrically conductive nonwoven fabric. Such a one-piece

Embodiment can be particularly easy to produce and assemble.

A particularly simple and cost-effective embodiment of the invention can be provided by the fact that the electrically conductive nonwoven fabric and the rolling bearing are bonded together.

According to a further advantageous embodiment of the invention, it is provided that the contacting element is formed at least in two parts and at least one support element and an insert element, wherein the T ragelement and the insert element connected to each other, in particular glued together. Such a multipart

or two-part embodiment of the Kontaktierelementes has regard to the retrofittability of existing systems and the flexibility of manufacturing advantages, since such a multi-part Kontaktierelement can be particularly easily glued outside the electric motor and then installed as a common component in the electric motor. A bond between the

Einlegeelement also provides a non-rotatable, stable and

inexpensive connection between the insert element and the support element. In the context of the present invention, a support element can be understood as a support body which is stiffer with respect to the insertion element and thus assumes a supporting function for the insertion element according to the invention. Such a support member may be formed, for example, of a metallic material.

It is also conceivable that the support element is formed from a plastic, insofar as it is suitable due to its material properties to provide a supporting effect for the insert element.

In the context of the present invention may further under a

Insertion element to be understood a component which is arranged in or on the support member and at least partially formed of an electrically conductive nonwoven fabric. The invention is not limited to a recessed in the support element insert element. Rather, it can also be foreseen that the insert element the

T ragelement at least partially engages.

Furthermore, the invention is not limited to a one-piece insert element. Thus, it may be provided according to the present invention that the insert element is designed in several parts. Essential to the invention here is only that the insert element forms the one component which is movable, or rotatably applied to rotating in operation components. A complete

Overlapping between the insert element and the abrading sliding contact surface is of course not necessary.

In an advantageous embodiment of the invention that is

Kontaktierelement and additionally or alternatively, the insert element formed as an annular disc. Such a flat disc can be provided in a space-saving manner under optimal utilization of the available space.

According to an advantageous embodiment of the invention may

be provided that the contacting element has an inner diameter which is smaller than the outer diameter of the motor shaft. In other words, the inner diameter of the

Kontaktierelementes is dimensioned according to an advantageous embodiment of the invention so that between the contacting and motor shaft, a press fit is formed. In this way, the radial contact pressure of the contacting can be increased to the lateral surface of the motor shaft in an advantageous manner and the reliability can be minimized accordingly. The optimized sliding properties of the electrically conductive nonwoven allow such increased radial pressure without this having a negative effect on the friction losses.

According to a further, particularly advantageous embodiment of the invention, the nonwoven fabric has a high lubricity and at the same time a small specific resistance, in particular a

resistivity less than 75W. Such a trained material allows a grinding contacting of components which rotate in operation at very high rotational speeds.

At the same time can by means of a material of the above

Characteristics of balancing potential differences between the rotor and the stator are provided secured. These advantageous material properties of the nonwoven fabric can be provided in particular in that the nonwoven fabric has a Teflon impregnation and is provided with metal particles, in particular with metal strips. By the use of metal particles respectively Metal strips which are incorporated into the nonwoven fabric, the electrical conductivity can be improved in an advantageous manner.

drawing

Embodiments of the invention are illustrated in the figures and explained in more detail in the following description. Show it:

Figure 1 is a schematic sectional view of a

Electric motor according to the invention with a

contacting element according to the invention,

Figure 2 is a detail of the electric motor according to the invention

analogous to Figure 1 in an enlarged view,

FIG. 3 is a perspective view of a contacting element according to the invention according to FIGS. 1 and 2,

4 shows a detail of the electric motor according to the invention

according to a second embodiment,

FIG. 5 is a perspective view of a contacting element according to the invention according to FIG. 3,

6 shows a further embodiment of a contacting element according to the invention in a perspective view.

description

FIG. 1 shows a sectional view of an electric motor 10 embodied by way of example as an external rotor motor. The electric motor can be used in particular as a fan motor in HVAC systems or for cooling an internal combustion engine in a vehicle or for driving a fan, a transmission, a pump or an actuator.

The electric motor 10 has a fixed part, the stator 12 and a rotating part, the rotor 14. An electric motor 10 of the external rotor motor type, as illustrated by way of example in FIG characterized by the fact that the radially inner part is fixed during operation, while the radially outer part rotates. On the stator 12, a plurality of windings 16 is arranged. The rotor 14 in turn has magnets 18. If the windings 16 are traversed by current, the magnetic field of the electric motor 10 is thereby generated.

It should be noted that the electric motor 10 is shown only schematically in Figure 1, since the structure and functionality of a suitable electric motor sufficiently well known in the prior art, so here for the sake of conciseness and simplicity of the description to an in-depth

Description of the electric motor 10 is omitted. Furthermore, it should be noted that the electric motor 10 merely by way of example and not for

Restriction of the invention is shown as an external rotor motor, since the invention can also be applied to an internal rotor motor.

The windings 16 of electric motors are fed in operation usually with pulse width modulated signals that can cause interference. As a rule, the electromagnetic interference radiation occurs at the windings 16 or the magnet 18. Starting from the windings 16 or magnets 18, the interference radiation can lead to disruption of other electronic systems and components which are arranged in the vicinity of the electric motor 10. In addition to influencing the environmental components by the electric motor 10, can in the reverse manner and interference from the

Environment affecting the electric motor 10 in its functionality. The electric motor 10 according to the invention should therefore shield windings 16 and magnets 18 as possible in all directions. In the case of an electric motor 10 of the external rotor type, as shown in FIG. 1, such a shield can be achieved inter alia by a rotor 14 arranged as close as possible to the stator 12. As can be clearly seen in Figure 1, the rotor 14 is formed substantially cup-shaped. This cup-shaped design of the rotor 14 in this case forms a shield for the windings 16 and magnets 18, which are arranged within the cup-shaped rotor 14. The cup-shaped rotor 14 has for this purpose in the radial direction

extending first section 20. This first portion 20 of the rotor 14 forms the bottom of the cup-shaped rotor 14. In addition to the first portion 20, the rotor 14 has a second portion 22 which is disposed on the outer edge of the rotor 14 and a circumferentially extending, in the axial direction Side wall of the cup-shaped rotor 14 forms.

The open area of the rotor 14 opposite the bottom 20 of the cup-shaped rotor 14 is shielded by a motor carrier 24, as can be seen clearly in FIG. The arrangement of the pot-shaped rotor 14 and the motor support 24 acting as a cover results in a substantially closed space, which is shielded in all directions by electrically conductive surfaces.

In the embodiment shown in Figure 1, the motor shaft 26 is rotatably connected to the motor carrier 24 and thus associated with the stator 12. Such a rotationally fixed connection can be provided in particular by injecting the motor shaft 26 into the motor carrier 24. As shown in Figure 1, the motor shaft 26 has a free end 30 and a rotation axis 32 about which the rotor 14 and the stator 12 are rotatably mounted to each other. Furthermore, the motor shaft 26 has a peripheral circumferential surface 27 extending in the axial direction. As already mentioned, the invention is not limited to one shown here Embodiment with a rotationally fixed in the stator 12 arranged motor shaft 26 limited. Rather, it is also conceivable that the motor shaft 26 is rotatably clamped in the rotor 14 and correspondingly the motor shaft 26 is associated with the rotor 14.

As shown in Figure 1, the axis of rotation 32 extends in the sense of an infinitely extending imaginary straight line in particular centrally through the motor shaft 26 and corresponds to the central axis of the motor shaft 26. For rotatable mounting of the rotor 14 relative to the stator 12 about the axis of rotation 32 points the pot-shaped rotor 14 on its side facing the motor shaft 26 a bearing seat 36, which in axial

Direction extends. Inside the bearing seat 36 of the rotor 14, a bearing 38 is arranged. As shown in Figure 1, the bearing 38 has two rolling bearings 40, 42, wherein both roller bearings 40, 42 sit with their respective outer ring 44 in the bearing seat 36 of the rotor 14 and with its corresponding inner ring 46 on the motor shaft 26.

In order to prevent the rotor 14 from assuming the function of a high-frequency antenna and possibly worsening the interference problem, the rotor 14 must be contacted with a ground potential 34. For this purpose, the rotor 14 must be electrically conductively connected to the motor shaft 26, which in turn is pressed into the motor carrier 24 and thus abuts the ground potential 34. Such a coupling between the rotor 14 and the motor shaft 26 can not be provided via the rolling bearings 40, 42 as a rule, since they have an oil-filled bearing gap, which has the consequence that no sufficiently stable ohmic connection can be provided.

In order nevertheless to provide a sufficiently stable connection between the rotor 14 and the motor shaft 26, an electrically conductive contacting element 48 is arranged between the stator 12 and the rotor 14. The Kontaktierelement 48 causes the reduction of potential differences between the rotor 14 and stator 12 of the electric motor 10 and is

According to the invention at least partially formed of an electrically conductive nonwoven fabric 52. One advantage is in particular that the nonwoven fabric 52 has fibers in a different orientation, so that they are arranged on a possible contact surface with different angles. In this way, despite a small radial contact force, a large contact surface can be built up.

Hereinafter, the fixedly clamped end 28 of the motor shaft 26 facing rolling bearing is referred to as the first roller bearing 40 and the free end 30 of the motor shaft 26 associated rolling bearings as the second rolling bearing 42.

It should be noted at this point that the illustrated in Figure 1

Rolling 40, 42 are only exemplified as a ball bearing. It is also conceivable that other basic forms of rolling bearings, such as cylindrical roller bearings, needle roller bearings or tapered roller bearings are used. However, all of these rolling bearing shapes have in common that rolling bodies between the inner ring 46 and an outer ring 44 reduce frictional resistance and because of lubrication or their nature they are unable to provide a sufficiently stable ohmic connection between the rotor 14 and the stator 12.

Furthermore, it is furthermore conceivable that such a contacting element 48 according to the invention, which is formed at least partially from an electrically conductive nonwoven fabric 52 of the type in question, is used in an electric motor 10 which is mounted by means of at least one sliding bearing. According to the concept of the invention, it may be provided that the contacting element according to the invention 48 rotatably connected to the at least one sliding bearing and on the lateral surface of the motor shaft and additionally or alternatively also on the end face of the sliding bearing to this movable, in particular rotatably rests.

As can be seen in Figure 1, the outer ring 44 of the first bearing 40 is clearly fixed in the axial direction in the embodiment shown here. For this purpose, the outer ring 44 of the first roller bearing 40 is fixed at its free end 30 of the motor shaft 26 facing side via a spacer sleeve 49. The function of the fuse in axial

Direction of the outer ring 44 at the, the free end 30 of the motor shaft 26 opposite side, assumes the bearing seat 38th

As can also be seen in FIG. 1, the second bearing 42 assumes the function of a fixed bearing, that is, it is capable of unambiguously positioning the motor shaft 26 in the axial direction. For this purpose, the second bearing 42 must be able to absorb both radial and axial forces and guide it into the surrounding construction. In the embodiment shown in Figure 1, the inner ring 46 of the second bearing 42 is fixed for this purpose on its the free end 30 of the motor shaft 26 facing side via a locking ring 50 on the motor shaft 26.

Of course, an inventive electric motor 10 is not limited to an axial fixation of the inner ring 46 via a locking ring 50. It can also be provided other security elements, such as nuts or lock washers. In order to take over the function of a fixed bearing, and the outer ring 44 of the second bearing 46 in the axial direction, that is in the extension direction of the rotation axis 32, fixed. In addition to the spacer sleeve 49 assumes the function of securing in the axial

Direction of the outer ring 44 a speed groove 51st The contacting element 48 according to the invention is integrally formed in the embodiment shown in Figure 1 from an electrically conductive nonwoven fabric 52 and rotatably connected to the outer ring 44 of the first rolling bearing 40. According to the one shown in FIG

Embodiment of the invention is the inventive

Kontaktierelement 48 and the electrically conductive nonwoven fabric 52 glued to this purpose in a support area 58 with the outer ring 44.

It should be mentioned at this point, however, that other non-rotating mounting variants of the invention

Kontaktierelementes 48 with one of the bearings 40,42 are conceivable. Thus, for example, it is also conceivable that the contacting element 48 is clamped between its outer ring 44 and the spacer sleeve 49 at its outer region, which is referred to below as the first section 62. The over the spacer sleeve 49th

Applied normal force on the support surface between the outer edge of the Kontaktierelementes 48 and the outer ring 44 of the first roller bearing 40 can prevent a displacement or rotation of the Kontaktierelementes 48 and the outer ring 44 to each other due to the counterforce caused by the static friction. It is considered to be particularly advantageous if, in this jammed support area 58, the contacting element 48 has a particularly high

Having friction coefficients. It is essential to the invention that the support area 58 between the contacting element 48 and the

Outer ring 44 of the rolling bearing 40 is so large that a sufficiently stable ohmic connection between the outer ring 44 and the contacting element 48 can be provided. To compensate for differences in potential between the rotor 14 and the stator 12 and the outer ring 44 and the motor shaft 26 is formed of an electrically conductive nonwoven fabric 52 annular disc in its inner region, which is referred to as the second section 64, on the inner ring 46th and additionally or alternatively thereto on the lateral surface 27 to this movable, in particular rotatable and thus forms a sliding contact by the formation of the sliding contact of an electrically conductive nonwoven fabric 52, which according to the invention particularly good

Sliding properties at the same time has sufficient electrical conductivity, the frictional losses, which occur especially in the area of the abrasive contact, can be minimized in an advantageous manner and at the same time a sufficiently stable ohmic connection between the rotor 14 and stator 12 are provided. According to an advantageous embodiment of the invention, the nonwoven fabric 52 has an electrical resistance which is less than 75 W. A particularly stable contact can be provided in particular by the contacting element 48 abutting both on the inner ring 46 of the rolling bearing 40 and on the lateral surface 27 in a grinding manner.

It should be mentioned at this point that the bearing assembly and securing the two rolling bearings 40, 42 can be modified or modified in many ways, without departing from the spirit

departing. So it is also conceivable that the

Contacting element 48 is arranged on the second bearing 42. In such an embodiment, it is conceivable, for example,

the speed groove 51 assumes the function of the contact element 48 according to the invention in addition to its support function. Furthermore, it is also conceivable that the contacting element 48 may be arranged on the end face 60 of the respective roller bearings 40, 42 facing away from the free end 30 of the motor shaft 26. Moreover, the invention is not limited to one Embodiment with only one contact element 48 limited. For example, it is also possible for a corresponding contacting element 48 to be arranged on both roller bearings 40, 42.

Figure 2 shows a section of the electric motor 10 according to the invention analogous to Figure 1. As already explained, the motor shaft 26 is rotatably mounted in the stator 12. For rotatable mounting of the rotor 14 relative to the stator 12 about the axis of rotation 32, a bearing seat 36 is formed on the rotor 14. At this bearing seat 36 of the outer ring 44 of the first bearing 40 abuts. The inner ring 46 of the same bearing 40 is substantially non-rotatably connected to the motor shaft 26. In order to compensate for potential differences between the stator 12 and rotor 14, a contacting element 48 is provided, which is in contact with the roller bearing 40 and rests against the lateral surface 27 of the motor shaft 26. Alternatively, it is also conceivable that the contacting element 48 on the end face 60 of the

Rolling, movable, in particular rotatably applied. Furthermore, it can also be provided that such a contact element 49 simultaneously, in particular rotatably, rests on both the lateral surface 27 of the motor shaft 26 and on the end face 60 of the rolling bearing. As can be seen in FIG. 2, the end face 60 of the roller bearing 40 represents that surface which is essentially perpendicular to the imaginary axis of rotation 32.

As already mentioned, the contact element 48 has a rotationally fixed manner to the rolling bearing 40 connected to the first section 62 and as

Slip contact formed and rotatably on the lateral surface 27 of the motor shaft 26 and additionally or alternatively also on the end face 60 of the rolling bearing 40 and the inner ring 46 of the rolling bearing 40 adjacent second section 64. The contacting element 48 shown in the embodiment according to FIG. 2 is produced in one piece from an electrically conductive nonwoven fabric 52. A nonwoven fabric 52 of the type in question here is preferably a material which with respect to its

Sliding properties has been optimized while having an optimized electrical conductivity. To provide these opposing properties, nonwoven fabric 52 preferably has one

Teflon impregnation on and is with metal particles, in particular

Provided with metal strips. Such a nonwoven fabric 52 is thus advantageously capable of abrading against the lateral surface 27 of the motor shaft 26 and alternatively or additionally to abut against the end face 60 of the rolling bearing 40 without increased friction losses occur.

As can be seen clearly in FIG. 2, the contacting element 48 according to the invention lies rotatably in the sense of a sliding contact both on the end face 60 of the roller bearing 40 and on the lateral surface 27 of the motor shaft 26. In the range of the movable or rotatable In the following, the rotatable, axial contacting of the Kontaktierelementes 48 and the second portion 64 of the Kontaktierelementes 48 with the end face 60 of the rolling bearing 40 is referred to as the first sliding contact surface 66 and the rotatable, radial

Contacting of Kontaktierelementes 48 and the second portion 64 of the Kontaktierelementes 48 with the lateral surface 27 of the motor shaft 26 as a second sliding contact surface 68th

Such an embodiment shown in FIGS. 1 and 2 having a contacting element 48 resting against both the first sliding contact surface 66 and the second sliding contact surface 68 has the advantage that, in the event of loss of contact with one of the two sliding contact surfaces 66, 68, the potential equalization over the

corresponding remaining contact can be made. In particular a slight lifting of the contacting element 48 from the first

Slip contact surface 66 can often occur during operation by start-up or shaking loads, so that the corresponding radial contact can maintain the function of balancing the potential differences. By such a two-sided contact on both sliding contact surfaces 66 and 68 can thus be advantageously increased the reliability. According to the present invention, it is also conceivable that the contacting element on the first

Sliding contact surface 66 or alternatively rotatably on the second sliding contact surface 68.

FIG. 3 shows the embodiment of the invention shown in FIG

invention

Kontaktierelementes 48 in a perspective view. The contacting element 48 shown in FIG. 3 is formed in one piece from an electrically conductive nonwoven fabric and has a substantially planar annular shape with a first section 62 arranged in the outer region and a second section 64 arranged in the inner region. In the mounted state, the axially extending inner surface with the axial height 70 on the lateral surface 27 of the

Motor shaft 26 contacting and forms the sliding contact surface 68th

In addition to such an essentially planar embodiment of the contacting element 48, it is also conceivable for the contacting element 48 to have an encircling collar in the region of the second section 64, which protrudes axially beyond the contour of the first section 62, so that the height 70 of the second sliding contact surface 68 and concomitantly the surface of the radial contact with the

Outer surface 27 of the stator 12 is increased in an advantageous manner. Such Kontaktierelement 48 with a circumferential collar has in particular with regard to the optimization of the target functions such as Size of the sliding contact surface and the contact pressure of the

Kontaktierelementes 48 to the end face 60 of the rolling bearing

or the lateral surface 27 of the motor shaft 26 advantages.

To the radial contact force of the Kontaktierelementes 48 to the

To increase lateral surface 27 of the motor shaft 28, it may be provided according to an embodiment of the invention that the

Inner diameter 72 of the contacting element 48 is dimensioned so that in the assembled state, the contacting element 48 with a

Press fit on the motor shaft 26 is seated. In other words, the inner diameter 72 of the Kontaktierelementes 48 is designed smaller than the outer diameter of the motor shaft 26. By the Teflon

or PTFE impregnation of the fibers of the nonwoven fabric 52, such an interference fit between the motor shaft 26 and the contact element 48 may be provided without this having a negative influence on the frictional losses.

Figure 4 shows a section of an electric motor 10 according to the invention according to Figure 2 with the difference that the inventive

Kontaktierelement is now formed in two parts. The

Contacting element 48 has a support element 74 and an insert element 76. The insert element 76 is formed from an electrically conductive nonwoven fabric 52. A support element 74 of the type in question may be a metal support element. However, it is also conceivable that the support element 74 is formed of a different material. In this case, it is only essential to the invention that the support element 74 has sufficient bending stiffness and thus a supporting structure for the nonwoven fabric 52

Insert element 76 offers. According to a possible embodiment of the invention it is

provided that the support member 74 and the insert member 76 are glued together. During assembly, for this purpose, the insert element 76 is first adhesively bonded to the support element 74 on the contact surface 80 that forms between these two components. Subsequently, the insert element 76 is pushed together with the support member 76 so far on the motor shaft 26 that the contact element 48 abuts with its support portion 58 on the outer ring 44 of the first bearing 40. Subsequently, the spacer sleeve 49 is pushed, which presses the first portion 62 of the Kontaktierelementes 48 against the outer ring 44. Essential to the invention here is that the support area 58 is so large that a sufficiently stable ohmic connection between the outer ring 44 and the contact element 48 can be provided. Of course, it is also conceivable that the insert element 76 is merely clamped in the support member 74, so that the additional manufacturing step of the bonding can be omitted. Furthermore, it is also conceivable that such a two-part

or multi-part contacting element in the region of the second rolling bearing 42 is arranged.

FIG. 5 shows the embodiment of the invention shown in FIG

invention

Kontaktierelementes 48 in a perspective view. As can be clearly seen in FIG. 5, the insert element 76 and the carrying element 74 terminate flush with one another in the axial direction. Both the insert element 76 and the support element 74 are formed according to the embodiment shown in Figure 5 as a substantially annular discs. It should be expressly mentioned at this point that it is also conceivable that the insert element 74 alternatively or additionally the support member 76 have a different shape in that they are suitable to provide the corresponding functionalities. As already explained at the beginning, it is provided that the second

Section 64 of the Kontaktierelementes 48, that is, the portion which rotatably on the end face 60 of the rolling bearing 40, 42 and additionally or alternatively thereto abuts the outer surface 27 of the motor shaft is formed of an electrically conductive nonwoven fabric 52. Due to the

provided functionalities of optimized lubricity and a minimized electrical resistance is such a nonwoven fabric 52 usually very costly. Accordingly, it can be provided according to the present invention, that the width 78 of the insert 76 is reduced in the radial direction, so that only a small disc of the electrically conductive nonwoven fabric 52 is inserted into the support member 74. Essential to the invention here is only that the support element 74 itself does not abrade against rotating components and here

Friction losses effected.

According to a further embodiment of the invention, it may further be provided that the insert element 76 projects beyond the contour of the support element 74 in the axial direction and, alternatively or additionally, covers the entire width 80 of the support element 74.

FIG. 6 shows a further embodiment of a contacting element 48 according to the invention in a perspective illustration. According to the embodiment of the contacting element 48 shown in FIG. 6, the contacting element 48 has an insertion element 76 and a

Support member 74, wherein the insert member 76 is formed in two parts. The two parts of the insert element 76 are also

formed circular segment. To clarify the now rotatable or abrasive applied area of the

Kontaktierelementes 48 is shown hatched in Figure 6. Such an embodiment of the insert element 76 allows in Advantageously, a further reduction of the required amount of nonwoven fabric 52. Of course, other forms of Einlegeelemente76 are conceivable. Thus, for example, it is also conceivable that the insert element 76 is formed from a plurality of individual insert segments.

Essential to the invention here is merely that sliding contact surfaces 66,

68 are sufficiently large to provide a sufficiently stable ohmic connection. The same applies accordingly for the dimensioning of the contact surface 58.

It should be noted that in terms of in the figures and in the

Description shown embodiments manifold

Possible combinations of the individual features are possible with each other. For example, the design of the

Kontaktierelementes 48 are adapted to the permissible relative speeds, friction coefficients and squeaking noises. Also the

Design of Kontaktierelements 48 as a one-piece or multi-part component and the type of non-rotatable mounting of

Kontaktierelementes rolling bearing can be adapted to product requirements such as the cost of the component or the retrofitting of an existing system.

Preferably, the electric motor 10 according to the invention drives

Combustion engine cooling fan on. However, the electric motor 10 can also be used in a pump, in particular a coolant pump, or an interior ventilation system of a vehicle.

Claims

claims

1. Electric motor (10), in particular external rotor motor, with a rotor (14), a stator (12) and a motor shaft (26), wherein the motor shaft (26) is associated with the stator (12) or the rotor (14) and a Rotary axis (32) around which rotor (14) and stator (12) to each other by means of at least one rolling bearing (40, 42), which has at least one end face (60) are rotatably mounted, and wherein the motor shaft (26) has a lateral surface (27) and between the rotor (14) and stator (12) a contacting element (48) is arranged, which is in contact with the at least one rolling bearing (40, 42) and on the lateral surface (27) of the motor shaft (26) and /or the

End face (60) of the rolling bearing (40, 42) to this movable, in particular rotatable, is applied, characterized in that the contacting element (48) is at least partially formed of an electrically conductive nonwoven fabric (52).

2. Electric motor (10) according to claim 1, characterized in that the contacting element (48) rotationally fixed to the at least one roller bearing (40, 42) is connected.

3. Electric motor (10) according to any one of the preceding claims, characterized in that the rolling bearing (40, 42) has an inner ring (46) and an outer ring (44), wherein the contacting element (48) rotatably connected to the outer ring (44) is and on the inner ring (46) movable, in particular rotatably rests.

4. Electric motor according to one of the preceding claims, characterized in that the contacting element (48) with the electrically conductive nonwoven fabric (52) on the end face (60) of the inner ring (46) of the Rolling bearing (40, 42) and / or the lateral surface (27) of the motor shaft (26) abradingly.

5. Electric motor (10) according to one of the preceding claims, characterized in that the motor shaft (26) rotatably connected to the stator (12), the inner ring (46) rotatably connected to the motor shaft (26) and the outer ring (44 ) abuts a bearing seat (36), wherein the bearing seat (36) on the rotor (14) is formed.

6. Electric motor (10) according to one of the preceding claims, characterized in that the contacting element (48) is integrally formed from an electrically conductive nonwoven fabric (52).

7. Electric motor (10) according to any one of the preceding claims, characterized in that the electrically conductive nonwoven fabric (52) and the rolling bearing (40, 42) are glued together.

8. Electric motor (10) according to one of the preceding claims, characterized in that the contacting element (48) is formed at least in two parts and at least one support element (74) and at least one insert element (76), wherein the support element (74) and the insert element (76) connected to each other, in particular glued together.

9. Electric motor (10) according to any one of the preceding claims, characterized in that the contacting element (48) and / or the

Insertion element (76) is designed as an annular disc.

10. Electric motor (10) according to one of the preceding claims, characterized in that the contacting element (48) has a

Inner diameter (72) which is formed smaller than the outer diameter of the motor shaft (26).

11. Electric motor (10) according to any one of the preceding claims, characterized in that the nonwoven fabric (52) has a high lubricity and a small resistivity, in particular a resistivity of less than 75 W.

12. Electric motor (10) according to any one of the preceding claims, characterized in that the nonwoven fabric (52) a

Teflon impregnation, wherein the nonwoven fabric (52) has metal parti cle, in particular metal strip.