DE102017213770A1 - electric motor - Google Patents

Abstract

The invention relates to an electric motor (10) having a stator (12), a rotor (14) and a motor shaft (20), wherein the motor shaft (20) has an axis of rotation (28) about which stator (12) and rotor (14 ) are rotatably mounted to each other by means of a bearing (32) and wherein the bearing (32) at least one axially resilient spring (50) which is adapted to receive axial forces between the rotor (14) and stator (12) and wherein at the stator ( 12) or on the rotor (14) a circumferential collar (44) is formed, which is suitable for the motor shaft (20) with its one end (24) rotatably clamped. It is proposed that the spring (50) is arranged at least partially axially in the region of the collar (44).

Description

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

State of the art

In order to be able to ensure adapted cooling for fan motors of different power classes, sheet metal packages and the magnetic circuit of the fan motors are generally lengthened to increase performance.

In the course of the increase in performance and concomitantly the use of extended laminated cores, however, the bearing distance of the motor shaft must be adjusted, as it too short bearing distance with too long fan motors due to the shift of the center of gravity otherwise to tumbling effects and concomitantly to a shortened life of the fan motor comes.

From the DE 10 2012 209 199 A1 It is known that the motor shaft has at a lower end a shoulder on which a compression spring is arranged, which absorbs forces of storage. The compression spring abuts with one end on the front side of the shoulder of the shaft.

Disclosure of the invention

The invention relates to an electric motor with a stator, a rotor and a motor shaft, wherein the motor shaft has an axis of rotation about which stator and rotor are rotatably supported by means of a bearing to each other and wherein the bearing has at least one axially elastic spring which is formed is to absorb axial forces between the rotor and stator and wherein on the stator or on the rotor, a circumferential collar is formed, which is suitable for the motor shaft with its one end clamped against rotation. It is proposed that the spring is arranged at least partially axially in the region of the collar.

The electric motor according to the invention has the advantage that the overall length of the electric motor can be minimized without reducing the clamping height of the rotationally fixed clamping of the motor shaft. Such a reduction in the length of the electric motor has a positive effect on the cost of an electric motor according to the invention.

Additionally or alternatively, the space savings of such an electric motor according to the invention can be used for the axial extension of storage, which has an advantageous effect on the tilting stability of the electric motor and the radial load of the storage. In particular, with an extension of the laminated cores can be collected by a prolonged storage in a particularly advantageous manner, the shifted focus. Thus, the electric motor according to the invention has an advantageous effect on the robustness of the system.

These two constructive, trade-off-related measures of storage extension and axial shortening of the overall length of the electric motor can be advantageously optimized, both separately and collectively, according to the set boundary conditions.

In the context of the present invention, an imaginary axis can be understood by a rotation axis about which a body, in particular the rotor, rotates in the sense of a rotation axis. In contrast to the axis of rotation, which represents a purely imaginary axis, with respect to the present invention, the term motor shaft, an objective machine element to be understood, which transmits a torque.

According to the invention, the motor shaft can be clamped in the stator. However, it is also conceivable that the motor shaft itself is clamped in the rotor and rotates together with the rotor in the stator. According to the arrangement of the rotationally fixed clamping in the stator or in the rotor, the circumferential collar may be formed on the stator or on the rotor.

In the context of the present invention, a circumferential collar can be understood as a projection extending in the axial direction, which projection is formed on the stator or on the rotor and is suitable for forming a rotationally fixed clamping for the motor shaft. For this purpose, it is not necessary that the circumferential collar is formed completely encircling. So it is also conceivable that the collar is partially formed circumferentially. Essential to the invention here is only that the collar is able to provide a non-rotatable clamping of the motor shaft via its contact surface to the motor shaft.

In the context of the present invention, an axially elastic spring can be understood as a structural element which is able to absorb work in the axial direction and store it in part or in part in strain energy.

The measures listed in the dependent claims, advantageous refinements and improvements of the given in the independent claims characteristics.

The electric motor according to the invention or an advantageous development draws This is due to the fact that the bearing has at least one bearing, wherein the at least one bearing is designed as a roller bearing. In particular, when using a bearing with two bearings, the tilt stability can be advantageously influenced by the fact that the bearing distance is increased. By such an electric motor according to the invention can be ensured that the motor shaft is clamped against rotation and at the same time the bearing distance can be increased at the same length. Furthermore, the concentricity error can be minimized in an advantageous manner over an increased bearing distance.

In an advantageous embodiment, the at least one bearing supports axially on the spring. In this way, the spring can advantageously apply a bias to the storage. In addition, the spring assumes the function of an axial stop for the rotor under load in the axial direction. Such biasing via a spring can reduce the risk of bearing damage that can be caused by vibration stress and wear due to cyclic eccentric loads.

In this context, the term "support" in addition to a direct concern also be understood that between the spring and the at least one bearing axially further components are arranged. Essential to the invention here is only that the spring absorbs axial forces of the bearing in the loaded state.

Such a spring may be formed according to an advantageous embodiment as a helical spring. In particular, by their small space requirement and their favorable spring characteristic is suitable in the context of the invention designed as a helical spring. In the context of the present invention, the term helical spring can also be understood to mean a tortuous torsion spring or spring.

In a particularly robust and simple embodiment of the spring this is designed according to the applied load as a helical compression spring. Furthermore, it is considered to be advantageous if the spring rests against the outer peripheral surface of the circumferential collar, from this way possible occurring longitudinal or transverse forces can be absorbed via the acting as a shoulder circumferential collar.

The term "abutment" can be understood in this context, a contact, which is subject to the usual tolerances and production-related deviations. Furthermore, it is also conceivable and optionally necessary for functional fulfillment that a narrow gap is arranged between the spring and the outer peripheral surface, so that the spring can spring in by friction on the outer circumferential surface without additional frictional losses. According to the invention, however, the spring is arranged no further than the width of a rolling bearing spaced from the peripheral surface of the circumferential collar. Moreover, it is also conceivable that the spring rests only partially on the outer peripheral surface.

In the context of the present invention, the outer circumferential surface can be understood to mean the surface of the circumferential collar which delimits the circumferential collar laterally, that is to say transversely to the imaginary axis of rotation. The outer circumferential surface thus corresponds geometrically to the outer circumferential surface of the circumferential collar.

In a preferred embodiment, the motor shaft may be injected into the circumferential collar. In this way, a stable non-rotatable connection between the motor shaft and the circumferential collar or the stator can be provided with particularly simple means.

In an advantageous embodiment, the motor shaft is rotatably mounted in the stator, the inner ring is axially movable on the motor shaft and the outer ring is non-rotatably on a bearing seat, wherein the bearing seat is formed on the rotor.

Furthermore, it is considered to be advantageous if the end face of the circumferential collar forms a stop for the bearing in the loaded state. In particular, in the formation of the at least one bearing as a rolling bearing with an inner ring and an outer ring, it may be provided that the inner ring of the at least one bearing contacted on the end face of the circumferential collar under load in the sense of a stop and thus forms the limiting end for maximum deflection ,

In this context, under the end face of the circumferential collar that surface can be understood, which limits the collar laterally in the direction of the axis of rotation. In other words, the end face extends substantially in the radial direction. The term end face is not limited to a flat surface, but the end face may have any surface contour.

A particularly robust embodiment and a particularly simple production and handling results from the fact that the stator and circumferential collar are integrally formed. Such a one-piece production offers advantages, in particular with regard to the production speed and the assembly effort. However, it should be mentioned at this point that a separate Manufacturing, followed by a subsequent Joining step of stator and circumferential collar, is conceivable.

In a further advantageous embodiment, a spacer is disposed axially between the bearing and the spring, which rests in the mounted state on the spring. The spacer sleeve in this case forms a stop for the bearing and thus advantageously limits the maximum axial deflection of the spring. Furthermore, the spacer sleeve can form the function of a Leitstützstruktur between the inner ring of the bearing and the spring and thus transmit the spring work in the radial direction.

In a further particularly advantageous embodiment of the electric motor according to the invention, at least one projection extending in the axial direction is arranged on the spacer disk. In the assembled state, the end face of the inner ring of the bearing is preferably located on this axial projection. In this way it can be ensured that rotating components of the bearing, such as a Lagerdeckscheibe not abutting the spacer disc. This can have a positive effect on noise minimization and friction losses in particular. Furthermore, it is also conceivable that a plurality of projections are arranged on the spacer, which are arranged distributed on the inner circumference.

list of figures

• 1 eine schematische Schnittdarstellung eines erfindungsgemäßen Elektromotors in einer Ausführungsform,
• 2 eine Ausschnitt des erfindungsgemäßen Elektromotors analog zu 1 in vergrößerter Darstellung,
• 3 eine perspektivische Explosionsdarstellung einer erfindungsgemäßen Distanzscheibe in einem Einbauzustand

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 in one embodiment,
• 2 a section of the electric motor according to the invention analogous to 1 in an enlarged view,
• 3 an exploded perspective view of a spacer according to the invention in an installed state

1 shows an example designed as an external rotor motor electric motor 10 in a sectional view. The electric motor 10 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 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 flows through current, so drives the magnetic field of the stator 12 the rotor 14 at.

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.

At the in 1 illustrated embodiment, the motor shaft 20 with the motor shaft diameter 22 rotatably with the stator 12 connected. Such a rotationally fixed connection can in particular by injecting the motor shaft 20 in the stator 12 and / or the circumferential collar 44 to be provided. As in 1 is shown, the motor shaft 20 a tightly clamped end 24 , a free end 26 and a rotation axis 28 on which the rotor 14 and the stator 12 are rotatably mounted to each other.

As in 1 is shown, the axis of rotation runs 28 in the sense of an infinite extending, imaginary straight line in particular centrally through the motor shaft 20 and corresponds to the center axis of the motor shaft 20 , For rotatable mounting of the rotor 14 opposite the stator 12 around the axis of rotation 28 is on the rotor 14 at its the motor shaft 20 facing side a bearing seat 30 arranged, which extends in the axial direction. Inside the warehouse seat 30 of the rotor 14 is a storage 32 arranged.

As in 1 is shown, indicates the storage 32 in one embodiment, two bearings 34 . 36 on, which are designed as rolling bearings. It should be mentioned at this point that a storage according to the invention 32 not on one, as in 1 illustrated embodiment limited to two bearings. So other types of bearings such as plain bearings for functional performance are conceivable.

As in 1 it can be seen, the two camps are sitting 34 . 36 with their respective outer ring 38 rotatably in the bearing seat 30 of the rotor 14 and with their corresponding inner ring 40 axially movable on the motor shaft 20 ,

In the following, this is the firmly clamped end 24 assigned bearings as the first bearing 34 and the free end 26 assigned bearings as second bearing 36 designated.

At the in 1 illustrated embodiment, the inner ring 40 of the second camp 36 at its free end 26 facing side by means of a locking ring 42 in the axial direction, that is along the axis of rotation 28 , on the motor shaft 20 fixed.

As in 1 can be clearly seen on the stator 12 a circumferential collar 44 formed. The in 1 illustrated, circumferential collar 44 has substantially the shape of a hollow cylinder with a circular base, wherein the inner peripheral surface 46 a receptacle for the motor shaft 20 forms. The in 1 illustrated circumferential collar 44 has a wall thickness 45 between 2.5mm and 3mm.

As in 1 can still be seen is axially in the region of the circumferential collar 44 a feather 50 arranged, at which the first camp 34 axially supported. At the in 1 illustrated embodiment is a coil spring, in particular a helical compression spring. However, it should be mentioned at this point that depending on the boundary conditions and the optimal spring characteristic, other springs such as spring washers or a set of spiral or coil springs can apply.

As already mentioned, the spring 50 axially in the region of the circumferential collar 44 arranged. This is the axially elastic spring 50 with its inner peripheral surface 52 on the outer peripheral surface 48 of the circumferential collar 44 at. About the axially elastic spring 50 is thus a bias on the mounting during assembly 32 applied. By such biasing the storage 32 the running noise can be reduced. At the in 1 illustrated embodiment, in particular, the inner ring 40 of the first camp 34 over the spring 50 biased.

By the arrangement of the spring 50 axially in the region of the circumferential collar 44 can the length 61 of the electric motor can be minimized without the clamping height 56 that is the axial section of the motor shaft 20 , which is firmly clamped to reduce. In addition to this, the space savings for axial extension of storage 32 or to extend the storage distance 62 be used.

2 shows a section of the electric motor according to the invention 10 in an enlarged view. As in 2 it can be seen, this is firmly clamped end 24 the motor shaft 20 axially from the circumferential collar 44 encompassed. Essential to the invention is that the clamping height 56 auseichend large dimensions. Preferably, the clamping height 56 larger than the motor shaft diameter 22 dimensioned. By such, sufficiently sized clamping height 56 can be ensured that the unilateral clamping of the motor shaft 20 capable of acting on the motor shaft 20 to absorb attacking forces and moments and to provide a non-rotatable and tilt-stable connection. In the 2 shown clamping has a clamping height 56 of about 10 mm.

At the in 2 illustrated embodiment, the clamping height is 56 from the axial height 58 of the circumferential collar 44 and an additional clamping area in the stator 12 together. It should be noted at this point, however, that an exclusive restraint in the circumferential collar 44 may also be conceivable, insofar as in such an embodiment, a sufficient clamping height 56 can be provided.

The surrounding collar 44 has in the embodiment shown here at the cross-sectional transition to the engine mount 22 a domed throat 60 for notch voltage optimization. At this throat 60 may be in a possible embodiment, the cross section of the first turn of the coil spring 50 invest.

2 shows an embodiment of an electric motor according to the invention in which stator 12 and circumferential collar 44 are made in one piece. However, it is also conceivable that the stator 12 and circumferential collar 44 be made in two pieces and in an additional manufacturing step of the circumferential collar 44 by means of a fastener on the stator 12 is attached.

As in 2 is shown, the coil spring is located 50 on the outer peripheral surface 48 of the circumferential collar 44 at. In other words, the coil spring 50 contacted with its inner peripheral surface 52 the outer peripheral surface 48 of the circumferential collar 44 , By positioning the axially elastic spring 50 above the surrounding collar 44 can the spring 50 can be optimally centered and lateral forces on the formed active surface pair between the outer peripheral surface 48 of the circumferential collar 44 and the spring 50 be recorded.

How out 2 can be seen, the first bearing is supported 34 axially on the spring 50 from. For this purpose, the camp lies 34 with his the stator 12 facing end face 37 at the frontal area 64 the feather 50 at. At the in 2 shown Embodiment is also between the stator 12 facing end face 37 of the first camp 34 and the face 64 the helical compression spring 50 a spacer 66 arranged. The spacer 66 serves the introduction of force between the axially elastic spring 50 and storage 32 or the first camp 34 ,

2 shows a load condition below the maximum load. At maximum load of the system becomes the spacer 66 against the face 49 of the circumferential collar 44 pressed and thus forms a stop for the rotor 14 ,

3 shows an exploded perspective view of a section of the electric motor 10 analogous to the 1 and 2 , As in 3 it can be seen is on the stator 12 in the middle of the axis of rotation 28 a circumferential collar 44 formed. The surrounding collar 44 , which has substantially the shape of a hollow cylinder, forms with the stator 12 a non-rotatable and tilt-stable mount for the motor shaft 22 , To provide such a firm restraint has the circumferential collar 44 a clamping height 56 on.

As in 3 continues to be clearly seen, is the spring 50 axially in the region of the circumferential collar 44 arranged. At the in 3 illustrated embodiment surrounds the axially elastic spring 50 for this purpose the circumferential collar 44 axially. The spacer 66 is in the assembled state with its the stator 12 facing end face 68 at the frontal area 64 the feather 50 at. To provide an improved bearing surface has the coil spring 50 on her face 64 a flattened support area.

At a maximum load of the electric motor according to the invention 10 contacts the spacer 66 the face 49 of the circumferential collar 44 , The surrounding collar 44 thus forms a stop and limits the maximum travel of the helical compression spring 50 in the direction of the axis of rotation 28 ,

How out 3 clearly shows the spacer 66 an annular shape, wherein the inner radius is approximately the inner radius of the bearing 34 equivalent. In 3 the spacer extends 66 in the radial direction only slightly beyond the center of the bearing. Essential to the invention here is that the spacer 66 on the end face of the spring 64 is applied and in this way a Leitstützstruktur between the storage 32 or the first camp 34 and the spring 50 forms.

In the area of the inner radius are at the the stator 12 opposite end face 68 the spacer 66 extending in the axial direction projections 70 arranged. These projections 70 are in the axial direction over the contour of the spacer 66 out. Will the bearing not shown here 34 when mounting on the shaft 20 pushed, so are the axial projections 70 at the frontal area 37 of the inner ring 40 of the camp 34 so that the rotating components of the bearing 34 , such as the Lagerabdeckscheiben, spaced from the stator 12 opposite end face 69 the spacer 66 are arranged.

As in 3 is shown, the projections 70 arranged circumferentially distributed in the region of the inner radius and have a substantially rectangular shape. It should be noted at this point that the number and arrangement of the projections 70 can be varied as desired. It is also conceivable, the projections 70 a different form than the one in 3 have shown shape. Thus, any shapes are conceivable which are suitable between the rotating components of the storage 32 and the spacer 66 provide an axial distance and thus a grinding of the storage 32 to prevent.

As in 3 is shown, has the spacer 60 next to the projections 70 also grooves 72 on. As in 3 is shown, the grooves are each circumferentially alternating with the projections 70 in the area of the inner radius of the spacer 66 arranged. It should be further noted at this point number, design and arrangement of the grooves according to the given boundary conditions can be varied. So it is conceivable, for example, that on the spacer 60 no grooves 72 are arranged.

It should also 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 design of the spring 50 and / or the circumferential collar 44 to the running behavior and load conditions of the electric motor 12 be adjusted. Furthermore, the embodiment spacer 66 be adapted to product requirements such as the cost of the component.

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 102012209199 A1 [0004]

Claims (12)

Electric motor (10) having a stator (12), a rotor (14) and a motor shaft (20), wherein the motor shaft (20) has a rotation axis (28) about which stator (12) and rotor (14) by means of a bearing (32) are rotatably mounted to each other and wherein the bearing (32) at least one axially resilient spring (50) which is adapted to receive axial forces between the rotor (14) and stator (12) and wherein on the stator (12) or on Rotor (14) is formed a circumferential collar (44) which is suitable for the motor shaft (20) with its one end (24) rotatably clamped, characterized in that the spring (50) at least partially axially in the region of the collar (44 ) is arranged. Electric motor (10) after Claim 1 , characterized in that the bearing (32) has at least one bearing (34,36), wherein the at least one bearing (34, 36) is designed as a rolling bearing. Electric motor (10) according to one of the preceding claims, characterized in that the at least one bearing (34, 36) is axially supported on the spring (50). Electric motor (10) according to one of the preceding claims, characterized in that the spring (50) is designed as a helical spring, in particular as a helical compression spring. Electric motor (10) according to one of the preceding claims, characterized in that the spring (50) on the outer peripheral surface (48) of the circumferential collar (44) rests. Electric motor (10) according to one of the preceding claims, characterized in that the motor shaft (20) in the circumferential collar (44) is injected. Electric motor (10) according to any one of the preceding claims, characterized in that the motor shaft (20) rotatably in the stator (12) is fixed, the inner ring (40) axially movable on the motor shaft (20) sits and the outer ring (38) against rotation a bearing seat (30) is applied, wherein the bearing seat (30) on the rotor (14) is formed. Electric motor (10) according to one of the preceding claims, characterized in that the end face (49) of the encircling collar (44) forms a stop for the bearing (34) in the loaded state. Electric motor (10) according to one of the preceding claims, characterized in that the stator (12) and circumferential collar (44) are integrally formed. Electric motor (10) according to any one of the preceding claims, characterized in that axially between the bearing (34) and spring (50) a spacer (66) is arranged, wherein the spacer (66) rests in the mounted state on the spring (50). Electric motor (10) according to one of the preceding claims, characterized in that on the spacer (10) at least one extending in the axial direction projection (70) is arranged. Electric motor (10) according to one of the preceding claims, characterized in that the at least one projection (70) rests in the mounted state on the end face (37) of the inner ring (40) of the bearing (34).

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