DE102017222281A1 - electric motor - Google Patents

Abstract

The invention relates to an electric motor (10), in particular an external rotor motor, with a rotor (14), a stator (12) and a motor shaft (26), the motor shaft (26) being associated with the stator (12) or the rotor (14) and an axis of rotation (32) about which rotor (14) and stator (12) are rotatably mounted to each other by means of at least one rolling bearing (40, 42) having at least one end face (60), and wherein the motor shaft (26) a lateral surface (27) and between the rotor (14) and the stator (12) a contact element (48) is arranged, which is in contact with the at least one roller 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. It is proposed that the contacting element (48) is formed at least partially from an electrically conductive nonwoven fabric (52).

Description

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 the DE 10 2012 201 545 A1 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 is based on 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 has an axis of rotation about which rotor and stator to each other by means of at least one rolling bearing, which at least has an end face, are rotatably mounted, and wherein the motor shaft has a lateral surface and between the rotor and a stator Kontaktierelement is arranged, which is in contact with the at least one rolling 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 rotatable, rests. 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 characteristics of the 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 contact element formed in this way advantageously friction and at the same time a stable ohmic connection to compensate for potential differences between the rotor and stator are provided. 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.

In the present case, the term "nonwoven fabric" can be understood to mean a fabric which consists wholly or to a substantial extent of fibers, these fibers being both staple fibers or filaments and / or fibers having a degree of slimming, that is to say 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, with respect to the present invention under
the term motor shaft understood an objective machine element
become.

Furthermore, in the context of the present invention, under an end face of
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, a surface of the motor shaft can be understood to mean that surface of the motor shaft which extends in the axial direction, that is to say in FIG Direction of the axis of rotation extends circumferentially. The term lateral surface is in this case not limited to a cylindrically planar surface, rather, the lateral surface may comprise projections and recesses.

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 a further 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. In particular, at a start of the electric motor, it may therefore be that such minimal 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, which are basically suitable for compensating for potential differences, due to the lubrication of the bearings, however, these are not a complete electrical line safely comply, resulting in a combination of such a rolling bearing with a contact element according to the invention Compensating potential differences proves to be particularly advantageous.
Furthermore, such contacting element is subject to low relative speeds, which has an advantageous effect on the loading of the contacting element and, consequently, on its service life.

According to an advantageous embodiment of the invention, this is the contacting 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 extends in a plane perpendicular or substantially perpendicular to the axis of rotation of the motor shaft. 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 when there is a loss of contact between one of the two sliding contact surfaces, the equipotential bonding can take place via the corresponding second sliding contact surface. In particular, a slight lifting of the Kontaktierelementes from the end face of the inner ring of the bearing can occur during operation by start-up movements of the electric motor or shaking loads, 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 one-piece embodiment is particularly easy to manufacture 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 support element and the insert element are connected to each other, in particular glued together. Such a multipart or two-part embodiment of the Kontaktierelementes has advantages in terms of retrofitting of existing systems and the flexibility of manufacturing, since such a multi-part contacting can be particularly easily glued outside the electric motor and then installed as a common component in the electric motor. An adhesive bond between the insert element also provides a non-rotatable, stable and cost-effective 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, an insert element can furthermore be understood as meaning a component which is arranged in or on the support element and is formed at least partially from 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 at least partially surrounds the support element.

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

In an advantageous embodiment of the invention, the contacting element and additionally or alternatively also the insert element is designed as an annular disc. Such a flat disc can be provided in a particularly space-saving manner with optimum utilization of the available installation space.

According to an advantageous embodiment of the invention, it 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, according to an advantageous embodiment of the invention, the inner diameter of the contacting element is dimensioned such that an interference fit is formed between the contacting element and the motor shaft. 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 specific resistance of less than 75 Ω. Such a trained material allows a grinding contacting of components which rotate in operation at very high rotational speeds. At the same time, the compensation of potential differences between the rotor and the stator can be provided secured by means of a material of the abovementioned properties. 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 or metal strips which are incorporated into the nonwoven fabric, the electrical conductivity can be improved in an advantageous manner.

list of figures

• 1 eine schematische Schnittdarstellung eines erfindungsgemäßen Elektromotors mit einem erfindungsgemäßen Kontaktierelement,
• 2 eine Ausschnitt des erfindungsgemäßen Elektromotors analog zu 1 in vergrößerter Darstellung,
• 3 eine perspektivische Darstellung eines erfindungsgemäßen Kontaktierelementes gemäß der 1 und 2,
• 4 eine Ausschnitt des erfindungsgemäßen Elektromotors gemäß einer zweiten Ausführungsform,
• 5 eine perspektivische Darstellung eines erfindungsgemäßen Kontaktierelementes gemäß 3,
• 6 eine weitere Ausführungsform eines erfindungsgemäßen Kontaktierelementes in einer perspektivischen Darstellung.

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

• 1 a schematic sectional view of an electric motor according to the invention with a contact element according to the invention,
• 2 a section of the electric motor according to the invention analogous to 1 in an enlarged view,
• 3 a perspective view of a Kontaktierelementes according to the invention according to the 1 and 2 .
• 4 a detail of the electric motor according to the invention according to a second embodiment,
• 5 a perspective view of a Kontaktierelementes according to the invention 3 .
• 6 a further embodiment of a contacting element according to the invention in a perspective view.

description

1 shows an example designed as an external rotor motor electric motor 10 in a sectional view. 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 on. An electric motor 10 of the type of external rotor motor, as exemplified in 1 is shown, characterized in that the radially inner part is fixed during operation, while the radially outer part rotates. At the stator 12 is a plurality of windings 16 arranged. The rotor 14 again has magnets 18 on. Be the windings 16 flowed through by electricity, so is the magnetic field of the electric motor 10 generated.

It should be noted that the electric motor 10 in 1 is shown only schematically, since structure and functionality of a suitable electric motor sufficiently well known in the prior art, so here for the purpose of conciseness and simplicity of the description to a detailed description of the electric motor 10 is waived. It should also be noted that the electric motor 10 merely by way of example and not to limit the invention as an external rotor motor, since the invention can also be applied to an internal rotor motor.

The windings 16 Electric motors are usually fed in operation with pulse width modulated signals that can cause interference. The electromagnetic interference occurs usually at the windings 16 or the magnet 18 on. Starting from the windings 16 or magnets 18 For example, the spurious radiations may interfere with other electronic systems and components operating in the vicinity of the electric motor 10 are arranged. In addition to influencing the environmental components by the electric motor 10 , In the opposite way, also interfering radiation from the environment can cause the electric motor 10 impair its functionality. The electric motor according to the invention 10 should therefore windings 16 and magnets 18 Shield as possible in all directions.

In an electric motor 10 of the type of an external rotor, as in 1 is shown, such a shield, inter alia, by a possible close to the stator 12 arranged rotor 14 be achieved. As in 1 can be clearly seen, is the rotor 14 essentially cup-shaped. This cup-shaped design of the rotor 14 This forms a shield for the windings 16 and magnets 18 which within the cup-shaped rotor 14 are arranged. The cup-shaped rotor 14 has for this purpose a radially extending in the first portion 20 on. This first section 20 of the rotor 14 forms the bottom of the cup-shaped rotor 14 , Next to the first section 20 , points the rotor 14 a second section 22 on, which at the outer edge of the rotor 14 is arranged and one, extending in the axial direction, circumferential side wall of the cup-shaped rotor 14 forms.

The ground 20 the cup-shaped rotor 14 opposite, open area of the rotor 14 will, as in 1 can be clearly seen, by a motor carrier 24 shielded. Due to the arrangement of the cup-shaped rotor 14 as well as acting as a cover engine carrier 24 This results in a substantially closed space, which is shielded in all directions by electrically conductive surfaces.

At the in 1 illustrated embodiment, the motor shaft 26 rotatably with the engine mount 24 connected and thus the stator 12 assigned. Such a rotationally fixed connection can in particular by injecting the motor shaft 26 in the engine mount 24 to be provided. As in 1 is shown, the motor shaft 26 a free end 30 and a rotation axis 32 on which the rotor 14 and the stator 12 are rotatably mounted to each other. Furthermore, the motor shaft 26 an axially extending, circumferential lateral surface 27 on. As already mentioned, the invention is not based on such an embodiment shown here with a rotation in the stator 12 arranged motor shaft 26 limited. Rather, it is also conceivable that the motor shaft 26 rotatably in the rotor 14 is clamped and accordingly the motor shaft 26 the rotor 14 assigned.

As in 1 is shown, the axis of rotation runs 32 in the sense of an infinite extending, imaginary straight line in particular centrally through the motor shaft 26 and corresponds to the center axis of the motor shaft 26 , For rotatable mounting of the rotor 14 opposite the stator 12 around the axis of rotation 32 has the cup-shaped rotor 14 at its the motor shaft 26 facing side a bearing seat 36 on, which extends in the axial direction. Inside the warehouse seat 36 of the rotor 14 is a storage 38 arranged. As in 1 is shown, indicates the storage 38 two rolling bearings on 40 . 42 on, both rolling bearings 40 . 42 with their respective outer ring 44 in the camp seat 36 of the rotor 14 and with their corresponding inner ring 46 on the motor shaft 26 sit.

To prevent the rotor 14 the function assumes a high-frequency antenna and possibly worsens the interference problem, the rotor must 14 to a ground potential 34 be contacted. For this purpose, the rotor must 14 with the motor shaft 26 electrically conductively connected, which in turn into the engine mount 24 is pressed in and thus at the mass potential 34 is applied. Such a coupling between the rotor 14 and the motor shaft 26 usually can not have the rolling bearings 40 . 42 be provided, since they have an oil-filled bearing gap, which has the consequence that no sufficiently stable ohmic connection can be provided.

Nevertheless, a sufficiently stable connection between the rotor 14 and motor shaft 26 is between the stator 12 and the rotor 14 an electrically conductive contacting element 48 arranged. The contacting element 48 causes the reduction of potential differences between rotor 14 and stator 12 of the electric motor 10 and is according to the invention at least partially made of an electrically conductive nonwoven fabric 52 educated. One particular advantage is that the nonwoven fabric 52 Having fibers in 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.

Subsequently, this is the firmly clamped end 28 the motor shaft 26 facing rolling bearings as the first rolling bearing 40 and the free end 30 the motor shaft 26 associated rolling bearings as a second rolling bearing 42 designated.

It should be noted at this point that the in 1 illustrated bearings 40 . 42 merely 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. All of these rolling bearing shapes, however, have in common that between the inner ring 46 and an outer ring 44 Rolling body reduce the frictional resistance and they are due to the lubrication or its nature are not capable of a sufficiently stable ohmic connection between the rotor 14 and the stator 12 provide.

Furthermore, it is furthermore conceivable that such a contact element according to the invention 48 which is at least partially made of an electrically conductive nonwoven fabric 52 the type in question here is formed in an electric motor 10 Application is found, 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 in 1 it can be seen, is the outer ring 44 of the first camp 40 clearly fixed in the axial direction in the embodiment shown here. For this purpose, the outer ring 44 of the first rolling bearing 40 at its free end 30 the motor shaft 26 facing side over a spacer sleeve 49 fixed. The function of securing in the axial direction of the outer ring 44 at the, the free end 30 the motor shaft 26 opposite side, takes over the bearing seat 38 ,

As in 1 can also be seen, takes over the second camp 42 the function of a fixed bearing, that is, it is capable of the motor shaft 26 to position clearly in the axial direction. The second camp 42 must be able to absorb both radial and axial forces and direct it into the surrounding structure. At the in 1 illustrated embodiment, the inner ring 46 of the second camp 42 for this purpose at its free end 30 the motor shaft 26 facing side over a retaining ring 50 on the motor shaft 26 fixed.

Of course, an inventive electric motor 10 not on an axial fixation of the inner ring 46 via a circlip 50 limited. It can also be provided other security elements, such as nuts or lock washers. To be able to assume the function of a fixed bearing is also the outer ring 44 of the second camp 46 in the axial direction, that is in the direction of extension of the axis of rotation 32 , fixed. Next to the spacer sleeve 49 assumes the function of securing in the axial direction of the outer ring 44 a speed groove 51 ,

The contacting element according to the invention 48 is in the in 1 illustrated embodiment in one piece of an electrically conductive nonwoven fabric 52 trained and rotationally fixed to the outer ring 44 of the first rolling bearing 40 connected. According to the in 1 illustrated embodiment of the invention is the contact element according to the invention 48 or the electrically conductive nonwoven fabric 52 for this purpose in a circulation area 58 with the outer ring 44 bonded.

However, it should be expressly mentioned at this point that other non-rotating fastening variants of the contacting element according to the invention 48 with one of the rolling bearings 40 . 42 are conceivable. For example, it is also conceivable that the contacting element 48 on its outside arranged area, which in the following as the first section 62 is designated, between the outer ring 44 and the spacer sleeve 49 is jammed. The over the spacer sleeve 49 applied normal force on the bearing surface between the outer edge of the contacting 48 and the outer ring 44 of the first rolling bearing 40 can due to the counterforce caused by the stiction a displacement or rotation of the contacting 48 and the outer ring 44 prevent each other. It is considered to be particularly advantageous if in this jammed support area 58 the contacting element 48 has a particularly high coefficient of friction. Essential to the invention is that the support area 58 between the contacting 48 and the outer ring 44 of the rolling bearing 40 so large is that a sufficiently stable ohmic connection between the outer ring 44 and the contacting element 48 can be provided.

To compensate for potential differences between the rotor 14 and the stator 12 or the outer ring 44 and the motor shaft 26 which is made of an electrically conductive nonwoven fabric 52 trained annular disc in its inner region, which hereinafter referred to as the second section 64 is designated on the inner ring 46 and additionally or alternatively, on the lateral surface 27 to this movable, in particular rotatable and thus forms a sliding contact. By forming the sliding contact of an electrically conductive nonwoven fabric 52 , which according to the invention has particularly good sliding properties at the same time 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 to be provided. According to an advantageous embodiment of the invention, the nonwoven fabric 52 an electrical resistance which is less than 75 Ω. A particularly stable contact can be provided in particular by the contacting element 48 both on the inner ring 46 of the rolling bearing 40 as well as on the lateral surface 27 abraded.

It should be mentioned at this point that the bearing arrangement and securing the two rolling bearings 40 . 42 can be modified or modified in many ways, without departing from the spirit. So it is also conceivable that the contacting 48 at the second camp 42 is arranged. In such an embodiment, it is conceivable, for example, that the speed groove 51 in addition to its support function, the function of the contacting element according to the invention 48 takes over. Furthermore, it is also conceivable that the contacting element 48 at the free end 30 the motor shaft 26 opposite end face 60 the respective rolling bearing 40 . 42 can be arranged. Moreover, the invention is not limited to an embodiment with only one contacting element 48 limited. For example, it is also possible that on both rolling bearings 40 . 42 a corresponding contacting element 48 is arranged.

2 shows a section of the electric motor according to the invention 10 analogous to 1 , As already explained, the motor shaft 26 rotationally fixed in the stator 12 attached. For rotatable mounting of the rotor 14 opposite the stator 12 around the axis of rotation 32 is on the rotor 14 a camp seat 36 educated. At this camp seat 36 is the outer ring 44 of the first camp 40 on. The inner ring 46 same warehouse 40 is essentially non-rotatable with the motor shaft 26 connected. To potential differences between stator 12 and rotor 14 compensate, is a contact element 48 provided, which in contact with the rolling bearing 40 stands and on the lateral surface 27 the motor shaft 26 is applied. Alternatively, it is also conceivable that the contacting element 48 at the frontal area 60 the rolling bearing movable, in particular rotatably rests. Furthermore, it can also be provided that such a contact element 49 both on the lateral surface 27 the motor shaft 26 as well as on the face 60 the rolling bearing simultaneously movable, in particular rotatably rests. As in 2 it can be seen, represents the face 60 of the rolling bearing 40 the surface which is substantially perpendicular to the imaginary axis of rotation 32 stands.

As already mentioned, the contacting element 48 a rotationally fixed with the rolling bearing 40 connected first section 62 and one designed as a sliding contact and rotatably on the lateral surface 27 the motor shaft 26 and additionally or alternatively also on the end face 60 of the rolling bearing 40 or the inner ring 46 of the rolling bearing 40 adjacent second section 64 on.

In the embodiment according to 2 illustrated contacting element 48 is in one piece from an electrically conductive nonwoven fabric 52 manufactured. For a nonwoven fabric 52 The type in question here is preferably a material which has been optimized with regard to its sliding properties and at the same time has an optimized electrical conductivity. To provide these opposing properties, the nonwoven fabric 52 Preferably, a Teflon impregnation and is provided with metal particles, in particular metal strips. Such a nonwoven fabric 52 is thus advantageously capable of grinding on the lateral surface 27 the motor shaft 26 and alternatively or additionally to the end face 60 of the rolling bearing 40 to be applied without increased friction losses.

As in 2 can be clearly seen, is the contact element according to the invention 48 both on the face 60 of the rolling bearing 40 as well as on the lateral surface 27 the motor shaft 26 rotatable in the sense of a sliding contact. In the range of the movable or rotating In the following is the rotatable, axial contacting of the contacting 48 or the second section 64 of the contacting element 48 with the front side 60 of the rolling bearing 40 as the first sliding contact surface 66 denotes and the rotatable, radial contacting of the contacting element 48 or the second section 64 of the contacting element 48 with the lateral surface 27 the motor shaft 26 as a second sliding contact surface 68 ,

Such in the 1 and 2 illustrated embodiment with one on both the first sliding contact surface 66 as well as on the second sliding contact surface 68 adjacent contact element 48 has the advantage that in case of loss of contact with one of the two sliding contact surfaces 66 . 68 the equipotential bonding can take place via the corresponding remaining contacting. In particular, a slight lifting of the contacting element 48 from the first sliding contact surface 66 can often occur during operation by start-up movements or shaking loads, so that the corresponding radial contacting 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 increased advantageously the reliability. According to the present invention, it is also conceivable that the contacting element on the first sliding contact surface 66 or alternatively on the second sliding contact surface 68 rotatably applied.

3 shows the in 2 shown embodiment of the contacting element according to the invention 48 in a perspective view. This in 3 illustrated contacting element 48 is formed in one piece from an electrically conductive nonwoven fabric and has a substantially planar annular shape with a first portion arranged in the outer region 62 and a second portion disposed inside 64 on. In the mounted state, the axially extending inner surface lies with the axial height 70 on the lateral surface 27 the motor shaft 26 contacting and forms the sliding contact surface 68 ,

In addition to such a substantially planar, embodiment of the Kontaktierelementes 48 It is also conceivable that the contact element 48 in the area of the second section 64 a circumferential collar, which axially over the contour of the first section 62 stands out so that the height 70 the second sliding contact surface 68 and concomitantly the surface of the radial contact with the lateral surface 27 of the stator 12 is advantageously increased. Such a contact element 48 With a circumferential collar has in particular with regard to the optimization of the target functions such as the size of the sliding contact surface and the contact pressure of the contacting element 48 to the face 60 of the rolling bearing or the lateral surface 27 the motor shaft 26 Advantages.

To the radial contact pressure of Kontaktierelementes 48 to the lateral surface 27 the motor shaft 28 To increase, 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 mounted state, the contacting element 48 with a press fit on the motor shaft 26 sitting. In other words, the inner diameter 72 of the contacting element 48 is 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 contacting element 48 be provided without this has a negative impact on the friction losses.

4 shows a section of an electric motor according to the invention 10 according to 2 with the difference that the contacting element according to the invention is now formed in two parts. The contacting element 48 has a support element 74 and an insert element 76 on. The insert element 76 is made of an electrically conductive nonwoven fabric 52 educated. In a support element 74 the type in question can be a metal support element. However, it is also conceivable that the support element 74 is formed of a different material. Essential to the invention is hereby only that the support element 74 has a sufficient bending stiffness and thus a supporting structure for the nonwoven fabric 52 trained insert element 76 offers.

According to a possible embodiment of the invention, it is provided that the support element 74 and the insert element 76 glued together. During assembly, the insert element is first used for this purpose 76 with the support element 74 at the forming between these two components contact surface 80 bonded. Subsequently, the insert element 76 together with the support element 76 far enough on the motor shaft 26 pushed that contacting element 48 with its support area 58 on the outer ring 44 of the first camp 40 is applied. Following is the spacer sleeve 49 deferred to the first section 62 of the contacting element 48 against the outer ring 44 pressed. Essential to the invention here is that the support area 58 so large is that a sufficiently stable ohmic connection between the outer ring 44 and the contacting element 48 can be provided. Of course, it is also conceivable that the insert element 76 only in the support element 74 is trapped, so that the additional manufacturing step of 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.

5 shows the in 4 shown embodiment of the contacting element according to the invention 48 in a perspective view. As in 5 can be clearly seen, close the insert element 76 and the carrying element 74 flush with each other in the axial direction. Both the insert element 76 as well as the support element 74 are according to the in 5 illustrated embodiment formed as a substantially annular discs. It should be mentioned at this point that it is also conceivable that the insert element 74 alternatively or additionally, the support element 76 another form in that they are suitable to provide the appropriate functionalities.

As already explained at the beginning, it is provided that the second section 64 of the contacting element 48 that is, the portion which is rotatable on the end face 60 of the rolling bearing 40 . 42 and additionally or alternatively, on the lateral surface 27 the motor shaft rests, made of an electrically conductive nonwoven fabric 52 is trained. Due to the provided functionalities of optimized lubricity and minimized electrical resistance is such a nonwoven fabric 52 usually very costly. Accordingly, it may 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 narrow slice of electrically conductive nonwoven fabric 52 in the support element 74 is used. Essential to the invention here is only that the support element 74 even not rubbing against rotating components and here causes friction losses.

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

6 shows a further embodiment of a contacting element according to the invention 48 in a perspective view. According to the in 6 illustrated embodiment of the contacting 48 has the contact element 48 an insert element 76 and a support element 74 on, wherein the insert element 76 is formed in two parts. The two parts of the insert element 76 are also formed circular segment. To illustrate the now rotatable or abrasive applied area of the contacting 48 is this in 6 hatched shown. Such an embodiment of the insert element 76 advantageously allows a further reduction of the required amount of nonwoven fabric 52 , Of course, other forms of Einlegeelemente76 are conceivable. For example, it is also conceivable that the insert element 76 is formed of a plurality of individual insert segments. Essential to the invention here is only 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, with regard to the exemplary embodiments shown in the figures and in the description, a variety of possible combinations of the individual features are possible with one another. For example, the configuration of the contacting element 48 adapted to the permissible relative speeds, coefficients of friction and squeaking noises. The embodiment of the contacting 48 as a one-piece or multi-part component and the type of rotationally fixed attachment of the contacting element on the 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 according to the invention drives 10 an engine cooling fan. The electric motor 10 However, it can also be used in a pump, in particular a coolant pump, or an interior ventilation system of a vehicle.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102012201545 A1 [0003]

Claims (12)

Electric motor (10), in particular an external rotor motor, with a rotor (14), a stator (12) and a motor shaft (26), the motor shaft (26) being associated with the stator (12) or the rotor (14) and an axis of rotation ( 32) around which rotor (14) and stator (12) are rotatably mounted to each other by means of at least one roller bearing (40, 42), which at least one end face (60), 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). Electric motor (10) after Claim 1 , characterized in that the contacting element (48) rotationally fixed to the at least one roller bearing (40, 42) is connected. 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) is non-rotatably connected to the outer ring (44) and on the inner ring (46) movable, in particular rotatably rests. 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) the motor shaft (26) abrading. Electric motor (10) according to any one of the preceding claims, characterized in that the motor shaft (26) rotatably connected to the stator (12) is connected, the inner ring (46) rotatably connected to the motor shaft (26) and the outer ring (44) a bearing seat (36) is applied, wherein the bearing seat (36) on the rotor (14) is formed. Electric motor (10) according to one of the preceding claims, characterized in that the contacting element (48) is formed in one piece from an electrically conductive nonwoven fabric (52). 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. 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 ) are connected to each other, in particular glued together. Electric motor (10) according to one of the preceding claims, characterized in that the contacting element (48) and / or the insert element (76) is designed as an annular disc. Electric motor (10) according to one of the preceding claims, characterized in that the contacting element (48) has an inner diameter (72) which is smaller than the outer diameter of the motor shaft (26). Electric motor (10) according to 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 Ω. Electric motor (10) according to one of the preceding claims, characterized in that the nonwoven fabric (52) has a Teflon impregnation, wherein the nonwoven fabric (52) has metal particles, in particular metal strips.

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