Motor

Abstract

The invention relates to an electric machine (1) having a rotor (2) with a rotor shaft (3) which extends in an axial direction (100); a first bearing element (4), in particular a rolling bearing, and a second bearing element (5), in particular a rolling bearing, which are each arranged on a bearing cap (13, 14) of the electric machine (1) for supporting the rotor shaft (3), the first bearing element (4) being fixedly arranged in a first bearing receptacle (13a) of the first bearing cap (13) with respect to the axial direction (100), and the second bearing element (5) being arranged in a second bearing receptacle (13b) of the first bearing cap (13) with respect to the axial direction (100). The second bearing element (5) is displaceably designed in a second bearing receptacle (14a) of the second bearing cap (14) with respect to the axial direction (100) and is supported relative to the second bearing cap (14) by means of at least one elastic restoring element (7), in particular a restoring spring, characterized in that the restoring element (7) is designed to exert an elastic restoring force on the second bearing element (5) in an action direction (200), wherein the direction of action (200) has a predefined angle (alpha) with respect to the axial direction (100), which angle is greater than 0 DEG and less than 90 DEG, in order to produce a preload both in the axial direction (100) and also in a radial direction (300) oriented perpendicular to the axial direction (100).

Description

Technical Field

[0001] This invention relates to an electric motor. In particular, this invention relates to an electric motor in which rotation is stabilized. Background Technology

[0002] An electric motor having a stator and a rotor is known from the prior art. The rotor has a rotor shaft, which is rotatably supported by bearings, typically using a fixed-floating-support assembly. The floating bearing used herein has a clearance fit with the bearing housing, thereby enabling axial movement of the floating bearing. Thus, the floating bearing can compensate for the axial expansion of the rotor, thereby preventing clamping in the bearing. The floating bearing is preloaded in the axial direction by an elastic element. Such a design is shown, for example, in DE 195 36 794 A1. Summary of the Invention

[0003] The motor according to the invention has reduced vibration. Furthermore, the bearing housing, especially the bearing housing of the floating bearing, has reduced wear. Particularly advantageously, reduced wear is achieved at the outer ring of the floating bearing and / or the bearing housing of the floating bearing and / or the outer ring of the preload element of the floating bearing. This eliminates the need for the steel sleeves used in the bearing housings of floating bearings in the prior art.

[0004] The motor has a rotor with a rotor shaft extending axially. Furthermore, the motor has a first bearing element, particularly a rolling bearing, and a second bearing element, also particularly a rolling bearing, which are respectively disposed at bearing covers of the motor to support the rotor shaft. Preferably, each bearing element is mounted at its own bearing cover. The bearing cover can also be, in particular, a can-shaped housing component of the motor.

[0005] A first bearing element is fixedly arranged axially in a first bearing receiving portion of a first bearing cover. A second bearing element is axially movable in a second bearing receiving portion of a second bearing cover. This achieves a fixed-floating-support assembly where the first bearing element forms a fixed bearing and the second bearing element forms a floating bearing. This reduces or avoids undesirable axial clamping of the rotor shaft.

[0006] The second bearing element is supported relative to the second bearing cap by at least one elastic reset element, in particular a reset spring.

[0007] Furthermore, a reset element is configured to apply an elastic reset force to the second bearing element along the direction of action, wherein the direction of action has a predetermined angle greater than 0° and less than 90° relative to the axial direction. In this way, the reset force generates preload not only along the axial direction but also along the radial direction oriented perpendicular to the axial direction.

[0008] Therefore, preload is achieved in both directions for the second bearing element. For example, the second bearing element can overcome the elastic restoring force of the reset element and move axially when the rotor shaft expands. Additionally, preload in the radial direction causes the second bearing element to be pressed into the second bearing housing. This prevents or reduces the circumferential movement, i.e., rotation, of the second bearing element, especially its outer ring, within the bearing housing, i.e., within the second bearing housing. The circumferential movement of the second bearing element would cause displacement of the rotor's center of gravity, which in turn generates vibration during motor operation. By avoiding or reducing such circumferential movement due to preload in the radial direction, vibration and wear are reduced or avoided.

[0009] The dependent claims illustrate preferred improvements to the invention.

[0010] Preferably, the second bearing element is constructed as a rolling bearing. The second bearing element particularly has an inner ring, an outer ring, and at least one rolling element located between the inner and outer rings. Preferably, multiple rolling elements exist between the inner and outer rings. The rolling elements are, for example, balls. Furthermore, it is preferable that the inner ring abuts against a protrusion on the rotor shaft and a reset element is provided for applying a reset force to the outer ring, or that the outer ring abuts against a protrusion on the rotor shaft and a reset element is provided for applying a reset force to the inner ring. The latter is advantageous, for example, in the case of a hollow shaft. A floating support utilizing the second bearing element is provided in the described manner, wherein the second bearing element is preloaded by the reset force of the reset element. This achieves optimal support, which on the one hand allows for fixed and reliable support, and on the other hand allows for tolerance compensation of the rotor shaft.

[0011] In an advantageous design, a wedge-shaped annular element is provided, which abuts against the inner or outer ring of the second bearing element, particularly with its first surface. The wedge-shaped annular element preferably abuts against the reset element with its second surface. Advantageously, the first and second surfaces of the annular element are arranged at a predetermined angle relative to each other. The wedge-shaped annular element is therefore preferably used as an adapter between the reset element and the inner or outer ring. Since the reset element can tilt relative to the central axis of the second bearing element to generate forces not only in the axial direction but also in the radial direction, the wedge-shaped annular element can compensate for this angular difference between the second bearing element and the reset element. This achieves easy assembly and reliable function of the second bearing element as a preloaded floating bearing. No particular requirements are placed on the shape of the second bearing element. It is only necessary to ensure that the radial force transmission can originate from the annular element and act on the outer ring, for example, through material locking and / or shape locking and / or adhesive action. Ideally, a standard outer ring is sufficient without modification and only needs to be correspondingly adapted to this annular element.

[0012] In another advantageous design, the inner or outer ring of the second bearing element abuts against the reset element using its second surface. Here, the second surface of the second bearing element is positioned at a predetermined angle relative to the axial direction. Therefore, compensation exists again between the direction of action of the reset element and the central axis of the second bearing element. Unlike a separate wedge-shaped ring element, no additional components are required. Only the corresponding ring of the second bearing element with the corresponding second surface, i.e., the inner or outer ring, needs to be constructed. This simplifies the assembly of the second bearing element because it minimizes the number of components.

[0013] The second bearing receiving portion of the second bearing cover preferably has a mating surface against which the reset element abuts, and this mating surface is constructed substantially parallel to the second surface. Thus, only a normal force acts between the surface of the second bearing receiving portion and the surface of the second bearing element, thereby simplifying the motor structure. Forces in both the axial and radial directions are generated by the second surface being inclined relative to the axial direction of the second bearing element, rather than being arranged perpendicularly.

[0014] Preferably, the outer ring of the second bearing element has a gap relative to the second bearing cap in the radial direction. Therefore, the second bearing element is not fixed but can move in the axial direction. Thus, the second bearing element is a floating bearing. Through preload due to the reset element, the second bearing element is preloaded both axially and radially. This makes the circumferential movement of the outer ring within the gap difficult or even prevents it.

[0015] In a preferred design, a wedge ring assembly is provided, comprising a first wedge ring and a second wedge ring. The first wedge ring abuts against the inner or outer ring of the second bearing element. The second wedge ring abuts against the second bearing cap. A reset element is arranged between the first and second wedge rings. By using the wedge ring assembly, no requirements are placed on the shape of the abutment surfaces, particularly. The shape of the second abutment surface ensures that the outer ring can absorb radial forces. Ideally, the outer ring is designed such that this force transmission is ensured by grooves in the wedge rings. The wedge ring assembly allows a reset force to be applied to the second bearing element in both the axial and radial directions.

[0016] Particularly advantageously, multiple individual springs distributed circumferentially in the wedge ring assembly are configured as reset elements. These individual springs are, in particular, helical springs. The individual springs are arranged oriented along their respective central axes, which have a predetermined angle relative to the axial direction. Specifically, the central axes are oriented perpendicular to the surface of the wedge ring assembly where the individual springs abut. The individual springs are preferably arranged in corresponding recesses of the first and / or second wedge rings to ensure reliable retention of the individual springs.

[0017] In an alternative design, the reset element is particularly advantageously a wave spring or a disc spring. The wave spring, or disc spring, is oriented along a spring axis, wherein the spring axis has a predetermined angle relative to the axial direction. The wave spring, or disc spring, can be advantageously held at and / or guided at the wedge ring by retaining and / or guiding elements.

[0018] Furthermore, it is preferably provided that the first and second wedge rings are arranged to resist rotation between each other by a torsion stop. The torsion stop is in particular at least one pin. Thus, the two wedge rings are constructed to be movable only relative to each other, so that a restoring force can be applied to the second bearing element by means of a restoring element.

[0019] Furthermore, the wedge ring assembly is preferably provided with a positioning element. Specifically, the positioning element is a positioning pin. The positioning element allows the first wedge ring and / or the second wedge ring to be held in a predetermined position relative to the second bearing cap. This avoids undesirable torsion of the first wedge ring and / or the second wedge ring, especially the wedge ring assembly. This results in reduced vibration of the motor during operation and reduced friction of the wedge ring assembly relative to the bearing cap.

[0020] In another preferred design, the second wedge ring and the second bearing housing have a press fit. This press fit prevents undesirable twisting of the second wedge ring relative to the second bearing housing, or at least avoids making it difficult. Therefore, it particularly prevents twisting of the wedge ring assembly in the second bearing housing, or at least makes it difficult. This results in reduced vibration of the motor during operation and reduced friction of the wedge ring assembly relative to the bearing housing. Attached Figure Description

[0021] Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In the drawings: Figure 1 A schematic diagram of a motor according to a first embodiment of the present invention is shown. Figure 2 A schematic detailed view of the rotor support of an electric motor according to a first embodiment of the present invention is shown. Figure 3 A schematic detailed view of a support assembly for the rotor of an electric motor according to a second embodiment is shown. Figure 4 A schematic detailed view of a support assembly for the rotor of an electric motor according to a third embodiment is shown, and Figure 5 A schematic detailed view of a support assembly for a motor rotor with a press fit, according to a fourth embodiment, is shown. Detailed Implementation

[0022] Figure 1 An image of a motor 1 according to a first embodiment of the invention is schematically shown. The motor 1 has a rotor 2 having a rotor shaft 3 extending along an axial direction 100. A first bearing cover 13 and a second bearing cover 14 are provided to support the rotor shaft 3. A first bearing element 4 is used to support the rotor shaft at the first bearing cover 13. For this purpose, the first bearing element 4 is fixedly arranged about the axial direction 100 in a first bearing receiving portion 13a of the first bearing cover 13. The first bearing element 4 is a rolling bearing; in the illustrated embodiment, the first bearing element 4 is exemplary a ball bearing. The first bearing element 4 has an inner ring 4a, an outer ring 4b, and a plurality of rolling elements 4c (e.g., balls). The first bearing element 4 forms a fixed bearing for supporting a fixed-floating-support assembly of the rotor shaft 3.

[0023] The second bearing element 5 is used to support the rotor shaft 3 at the second bearing cover 14. The second bearing element 5 is constructed as a rolling bearing and has an inner ring 5a, an outer ring 5b, and at least one rolling element 5c located between the inner ring 5a and the outer ring 5b. In the illustrated embodiment, the second bearing element 5 is a ball bearing. The second bearing element 5 is movably constructed in the second bearing receiving portion 14a of the second bearing cover 14 about axial direction 100. Therefore, the second bearing element 5 forms a floating bearing in the fixed-floating-support structure of the rotor shaft 3.

[0024] Figure 2 A schematic detailed view is shown of the support of the rotor shaft 3 of the motor 1 by the second bearing element 5 according to a first embodiment of the present invention.

[0025] The second bearing element 5 is supported relative to the second bearing cover 14 by at least one elastic reset element 7. The second bearing element 5 is preloaded in this way, otherwise it would be loosely arranged in the second bearing receiving portion 14a. Specifically, the reset element is a reset spring. In the illustrated embodiment, the inner ring 5a is arranged abutting against the protrusion 3a of the rotor shaft 3, and the reset element 7 is configured to apply a reset force to the outer ring 5b.

[0026] The reset element 7 is configured to apply an elastic reset force to the second bearing element 5 along the direction of action 200. The direction of action 200 has a predetermined angle α greater than 0° and less than 90° relative to the axial direction 100, so as to generate preload not only along the axial direction 100, but also along the radial direction 300 perpendicular to the axial direction 100. This presses the outer ring 5b of the second bearing element 5 against the second bearing receiving portion 14a along the radial direction 300. Furthermore, since the second bearing element 5 is configured as a floating bearing, the outer ring 5b of the second bearing element 5 has a gap 12 along the radial direction 300 relative to the second bearing cover 14. The preload along the radial direction 300 caused by the reset element 7 prevents or reduces the circumferential movement of the second bearing element 5 in this gap 12. This reduces or avoids the vibration of the rotor 2 during the operation of the motor 1, and reduces or prevents wear on the second bearing cover 14 and / or the second bearing element 5, especially the outer ring 5b and the reset element 7.

[0027] In a first embodiment, an elastic restoring force is applied to the second bearing element 5 along the direction of action 200 using a wedge-shaped annular element 8, the annular element abutting against the outer ring 5b of the second bearing element 5 with its first surface 8a. The wedge-shaped annular element 8 abuts against the reset element 7 with its second surface 8b. The first surface 8a and the second surface 8b of the annular element 8 have a predetermined angle α relative to each other. In an alternative design, the outer ring 5b of the second bearing element 5 can be specially fitted and directly abutted against the reset element 7 using its second surface 8b, wherein, in this case, the second surface 8b of the second bearing element 5 has a predetermined angle α relative to the axial direction 100. Conversely, the use of a separate annular element 8 allows for the use of commercially available rolling bearings, such as, for example, commercially available ball bearings.

[0028] Furthermore, the second bearing receiving portion 14a of the second bearing cover 14 has a mating surface 6, against which the reset element 7 abuts. The mating surface is constructed substantially parallel to the second surface 8b. Therefore, only the normal force acts on the mating surface 6 and the second surface 8b. The design of the mating surface 6 and the second surface 8b, that is, their orientation, results in the normal direction of these surfaces being the direction of action 200. Therefore, the second bearing element 5 is preloaded not only along the axial direction 100 but also along the radial direction 300. The wedge-shaped annular element 8 serves as an adapter between the reset element 7, oriented along the direction of action, and the outer ring 5b of the second bearing element 5, whose outer surface has the axial direction 100 as the normal direction.

[0029] In the first embodiment, the second bearing receiving portion 14a is adapted to the desired direction of action 200 of the elastic reset element 7 via a specially fitted mating surface 6. In the second and third embodiments described below, this special adaptation of the second bearing receiving portion 14a is omitted. This is achieved through the wedge ring assembly 9. Figure 3 A detailed view of the support assembly for the rotor 2 of the motor 1 according to a second embodiment of the invention is schematically shown. Here, the basic structure is the same as in the first embodiment, the main difference being the mounting method of the reset element 7, which in this embodiment is integrated into the aforementioned wedge ring assembly.

[0030] The wedge ring assembly 9 has a first wedge ring 9a and a second wedge ring 9b, wherein the first wedge ring 9a abuts against the outer ring 5b of the second bearing element 5. The second wedge ring 9b abuts against the second bearing cap 14. A reset element 7 is arranged between the first wedge ring 9a and the second wedge ring 9b. In this way, the reset element 7 operates along a direction of action 200 having a predetermined angle α relative to the axial direction 100. In a second embodiment, a plurality of individual springs 7a distributed circumferentially in the wedge ring assembly 9 are configured as reset elements 7. Each individual spring 7a is oriented along a corresponding central axis 400, wherein the central axis 400 has a predetermined angle α relative to the axial direction 100. The individual springs 7a are, in particular, helical springs.

[0031] The use of the wedge ring assembly 9 enables pre-tightening of the second bearing element 5 along the axial direction 100 and the radial direction 300 in conventionally manufactured bearing covers. In the conventional structure, the reset element is oriented axially and arranged between the second bearing element 5 and the second bearing receiving portion 14a. This conventional reset element can be replaced by the wedge ring assembly 9 as described, thereby orienting the elastic reset force of the reset element 7, or the single spring 7a, along the direction of action 200. Therefore, the motor structure is simple and low-cost.

[0032] As described above, the outer ring 5b of the second bearing element 5 has a gap 12 in the radial direction 300 relative to the second bearing cap 14. A second gap 12a exists between the first wedge ring 9a and the second bearing cap 14, and a third gap 12b exists between the second wedge ring 9b and the bearing cap 14. Therefore, the wedge rings 9a and 9b are received in the second bearing receiving portion 14a in this embodiment by a clearance fit. To prevent the wedge rings 9a and 9b from twisting relative to each other, the first wedge ring 9a and the second wedge ring 9b are arranged to resist rotation with each other by a torsion stop 10. The torsion stop is in particular at least one pin, which, for example, is embedded not only in the hole of the first wedge ring 9a but also in the hole of the second wedge ring 9b. In addition, the wedge ring assembly 9 has a positioning element 11. In particular, the positioning element 11 is a positioning pin. The positioning element 11 is used to hold the first wedge ring 9a and / or the second wedge ring 9b in a predetermined position relative to the second bearing cap 14. This ensures that the direction of action 200 always corresponds to the pre-determined and definite direction.

[0033] Figure 4 A detailed view of the support assembly for the rotor 2 of the motor 1 according to a third embodiment of the invention is schematically shown. Here, the basic structure is the same as in the second embodiment. However, in the third embodiment, instead of the single spring 7a, the reset element 7 is a wave spring 7b or a disc spring. The wave spring 7b or disc spring is oriented along the spring axis 500, wherein the spring axis 500 has a predetermined angle α relative to the axial direction 100. The wave spring 7b or disc spring is held and / or centered, in particular, by the directional element 16. The third embodiment is functionally the same as the second embodiment, only the manner in which the elastic reset force is generated differs due to the different design of the reset element 7. In the third embodiment, a torsion stop 10 and / or positioning element 11 as described above are also preferably provided.

[0034] Figure 5 A detailed view of the support assembly for the rotor 2 of the motor 1 according to a fourth embodiment of the invention is schematically shown. Here, the basic structure is the same as in the third embodiment. However, in the fourth embodiment, instead of the positioning element 11, a press fit 17 is provided between the second wedge ring 9b and the second bearing receiving portion 14a, which secures the second wedge ring 9b in the second bearing cover 14 in a torsion-resistant manner.

Claims

1. An electric motor (1) having: A rotor (2) with a rotor shaft (3) extending along the axial direction (100); The first bearing element (4), particularly a rolling bearing, and the second bearing element (5), particularly a rolling bearing, are respectively disposed at the bearing caps (13, 14) of the motor (1) to support the rotor shaft (3). wherein The first bearing element (4) is fixedly arranged in the first bearing receiving portion (13a) of the first bearing cover (13) about the axial direction (100). The second bearing element (5) is movably constructed in the second bearing receiving portion (14a) of the second bearing cover (14) about the axial direction (100) and is supported relative to the second bearing cover (14) by at least one elastic reset element (7), in particular a reset spring. The characteristic feature is that the reset element (7) is configured to apply an elastic reset force to the second bearing element (5) along the action direction (200), wherein the action direction (200) has a predetermined angle (α) greater than 0° and less than 90° relative to the axial direction (100) so as to produce preload not only along the axial direction (100) but also along the radial direction (300) perpendicular to the axial direction (100).

2. The electric machine (1) according to claim 1, characterized in that The second bearing element (5) is constructed as a rolling bearing and has an inner ring (5a), an outer ring (5b) and at least one rolling element (5c) between the inner ring (5a) and the outer ring (5b), wherein the inner ring (5a) abuts against a protrusion (3a) of the rotor shaft (3) and the reset element (7) is configured to apply the reset force to the outer ring (5b), or the outer ring (5b) abuts against a protrusion (3a) of the rotor shaft (3) and the reset element (7) is configured to apply the reset force to the inner ring (5a).

3. The electric machine (1) according to claim 2, characterized in that A wedge-shaped annular element (8) abuts against the inner ring (5a) or outer ring (5b) of the second bearing element (5) with its first surface (8a) and its second surface (8b) abuts against the reset element (7), wherein the first surface (8a) and the second surface (8b) of the annular element (8) have a predetermined angle (α) relative to each other.

4. The electric machine (1) according to claim 2, characterized in that The inner ring (5a) or outer ring (5b) of the second bearing element (5) abuts against the reset element (7) with the second surface (8b), wherein the second surface (8b) of the second bearing element (5) has a predetermined angle (α) relative to the axial direction (100).

5. An electrical machine according to claim 3 or 4, characterised in that, The second bearing receiving portion (14a) of the second bearing cover (14) has a mating surface (6), the reset element (7) abuts against the mating surface, and the mating surface is constructed substantially parallel to the second surface (8b).

6. The electric machine (1) according to any one of claims 2 to 5, characterized in that The outer ring (5b) of the second bearing element (5) has a gap (12) relative to the second bearing cap (14) in the radial direction (300).

7. The electric machine (1) according to any one of claims 2 to 6, characterized in that A wedge ring assembly (9) having a first wedge ring (9a) and a second wedge ring (9b), wherein the first wedge ring (9a) abuts against the inner ring (5a) or outer ring (5b) of the second bearing element (5), wherein the second wedge ring (9b) abuts against the second bearing cap (14), and wherein the reset element (7) is arranged between the first wedge ring (9a) and the second wedge ring (9b).

8. The electric machine (1) according to claim 7, characterized in that Multiple individual springs (7a), particularly helical springs, distributed circumferentially on the wedge ring assembly (9) are configured as reset elements (7), which are oriented along a corresponding central axis (400), wherein the central axis (400) has a predetermined angle (α) relative to the axial direction (100).

9. The electric machine (1) according to claim 7, characterized in that The reset element (7) is a wave spring (7b) oriented along the spring axis (500), wherein the spring axis (500) has a predetermined angle (α) relative to the axial direction (100).

10. The electric machine (1) according to any one of claims 7 to 9, characterized in that, The first wedge ring (9a) and the second wedge ring (9b) resist each other from rotation by means of a torsion stop (10), particularly by means of at least one pin.

11. The electric machine (1) according to any one of claims 7 to 10, characterized in that The wedge ring assembly (9) has a positioning element (11), particularly a positioning pin, to hold the first wedge ring (9a) and / or the second wedge ring (9b) in a predetermined position relative to the second bearing cap (14).

12. The electric machine (1) according to any one of claims 7 to 11, characterized in that The second wedge ring (9b) has a press fit (17) to hold the wedge ring assembly (9) in a predetermined position relative to the second bearing cap (14).

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