Motor

Abstract

The invention relates to an electric machine having a rotor shaft (4), a floating bearing (1) and a bearing cover (3), the floating bearing (1) being provided for rotatably supporting the rotor shaft (4), the floating bearing (1) having an inner ring and an outer ring, the outer ring of the floating bearing being received in a bearing receptacle formed in the bearing cover (3), the inner ring being mounted on the rotor shaft (4), and the bearing cover (3) being provided with an outer ring. The elastic gasket (2) is arranged between the outer ring and the bearing cover in the axial direction, and the elastic gasket (2) is provided with a coating at least on a first surface area and a second surface area.

Description

Technical Field

[0001] The present invention relates to a motor. Background Art

[0002] It is known to use at least two bearings, in particular rolling bearings, for supporting a shaft.

[0003] An electric motor is known from DE 20 2007 009 954 U1 as the closest prior art.

[0004] A bearing arrangement with axially preloaded ball bearings for an electric motor is known from EP 2 902 648 A1.

[0005] An electric motor is known from DE 10 2011 119 603 A1.

[0006] A torsional vibration damper with an adjustable friction coefficient is known from DE 10 2020 120 389 A1.

[0007] DE 10 2019 207 290 A1 discloses a friction brake body for a friction brake of a motor vehicle.

[0008] EP 1 711 642 B1 discloses an iron-containing layer applied to a sliding surface by thermal spraying.

[0009] A controlled powder welding process is known from DE 10 2018 130 798 A1.

[0010] DE 10 2020 006 831 A1 discloses an electric motor having a fan cover, a rotor shaft rotatably mounted relative to the fan cover, and an angle sensor.

[0011] An electric motor is known from DE 10 2008 028 607 A1. Summary of the Invention

[0012] The object of the present invention is therefore to improve an electric machine, the operation of which is as safe as possible.

[0013] According to the invention, this object is achieved by an electric machine according to the features of claim 1 .

[0014] The important feature of the present invention in terms of the motor is that the motor has a rotor shaft, a floating bearing and a bearing cover.

[0015] The floating bearing is provided for rotatably supporting the rotor shaft.

[0016] The floating bearing comprises an inner ring and an outer ring, in particular wherein the rolling elements are arranged between the inner ring and the outer ring.

[0017] The outer ring of the floating bearing is accommodated in a bearing receptacle formed in, in particular molded into, the bearing cover, in particular a pot-shaped bearing receptacle and / or a blind hole.

[0018] Among them, the inner ring is mounted on the rotor shaft.

[0019] The elastic washer is arranged in the axial direction between the outer ring and the bearing cover, in particular the bottom of the bearing receiving portion.

[0020] The elastic gasket is coated or roughened by sandblasting or laser structured at least on the first surface area and the second surface area, and in particular has ridges extending more in the radial direction than in the circumferential direction.

[0021] The advantage here is that safe operation is achieved by preventing the outer ring of the floating bearing from rotating or slipping. On the one hand, the outer ring of the floating bearing is arranged to be axially displaceable, thereby compensating for thermally induced changes in the axial length of the shaft. On the other hand, the outer ring is non-rotatably connected to the bearing receptacle of the bearing cap, thus preventing circumferential rotation of the outer ring. Despite axial deflection of the elastic disk due to thermally induced changes in the axial length, the elastic disk prevents circumferential rotation of the outer ring. This is achieved by increased adhesion and friction—especially compared to an uncoated elastic disk (made from sheet steel and received in a steel bearing receptacle), which can be achieved by coating and / or roughening, where the outer ring is also made of steel. Consequently, even a simple rubber coating of the elastic disk achieves high adhesion between the disk and the bearing cap, and between the disk and the outer ring. However, if an adhesive is used as a coating at the contact points between the spring washer and the bearing cover and between the spring washer and the outer ring, a particularly rotationally fixed connection can be achieved and thus slipping or rolling of the outer ring can be prevented.

[0022] The first surface areas are particularly spaced apart from one another in the circumferential direction, and the second surface areas are spaced apart from one another in the circumferential direction. Furthermore, the first surface areas are arranged axially on the front side of the elastic washer, while the second surface areas are arranged axially on the rear side of the elastic washer. This advantageously achieves increased static friction in the contact area of ​​the elastic washer both on the front side and on the rear side in the axial direction.

[0023] In particular, because the elastic gasket is implemented as an annular perforated gasket with a circumferential edge region extending in a wavy manner in the axial direction, it can also be called an elastic wave gasket. Therefore, as the circumferential angle increases, the axial position of the elastic gasket fluctuates. In other words, the axial position of the elastic gasket is a periodic function of the circumferential angle.

[0024] Instead of a coating, the surface can also be roughened, in particular by sandblasting or laser structuring. In the case of laser structuring, it is advantageous to produce thin structures in the micrometer range in the radial direction so that static friction effectively prevents the elastic washer or the outer ring of the floating bearing from rotating.

[0025] In an advantageous embodiment, the elastic washer rests both on the bearing cover (in particular the bottom of the bearing receptacle) and on the outer ring. This has the advantage that increased adhesion and thus increased rotational resistance can be achieved.

[0026] In one advantageous embodiment, the axial position of the elastic washer, in particular the axial position of the median of the area covered by the elastic washer in the axial direction, is a periodic function, in particular a non-zero function, of the circumferential angular position. This advantageously results in the elastic washer oscillating back and forth periodically in the axial direction as the circumferential angle increases. Consequently, installing the elastic washer between the outer ring and the bearing receptacle results in an elastic deflection of the elastic washer, which in turn adjusts or generates the bearing preload. The ring axis, in particular the central axis of the elastic washer, is parallel to the axial direction.

[0027] In one advantageous embodiment, the outer ring is received in the bearing receptacle with an interference fit. This has the advantage that the floating bearing, in particular the outer ring of the floating bearing, can move in the axial direction in the event of thermally induced changes in the length of the rotor shaft. Maintaining a correspondingly low static friction is crucial. This can be achieved by designing the bearing receptacle to be sufficiently loose so that the outer ring can be received with an interference fit, with the tolerance range of the transition fit allowing axial movement of the floating bearing in the event of thermally induced changes in length. However, in order to prevent the outer ring from rotating in the circumferential direction relative to the axis of rotation of the rotor shaft in such a loosely designed bearing receptacle, the coating of the elastic washer is selected so that the outer ring is connected to the bearing cover, in particular in the bearing receptacle, in a rotationally fixed manner via the elastic washer.

[0028] In an advantageous embodiment, the outer ring is received in the bearing receptacle with a precise fit / transition fit, so that the static friction torque generated in the operative connection between the outer ring received in the bearing receptacle and the bearing cover is smaller than the static friction torque that can be generated by any or all of the operative connections to the outer ring by means of the elastic washers, and also smaller than the static friction torque that can be generated by any or all of the operative connections to the bearing cover by means of the elastic washers. This has the advantage that, while, on the one hand, a rotationally fixed, materially bonded, and / or force-locking connection between the outer ring and the bearing cover is achieved by means of the elastic washers, on the other hand, an axial displacement of the floating bearing can be achieved without or with only minimal force.

[0029] In an advantageous embodiment, the coating is an adhesive, a rubber layer and / or a plastic layer. The advantage here is that a friction-locking and / or material-locking, rotationally fixed connection between the outer ring and the bearing cover can be achieved by means of the elastic washer.

[0030] In an advantageous embodiment, the first surface area provided with the coating is the area of ​​the spring washer that is furthest from the outer ring. This has the advantage that only a low expenditure of material is required, since only the contact areas between the spring washer and the outer ring and between the spring washer and the bearing cap need to be coated.

[0031] In an advantageous embodiment, the second surface area provided with the coating is the area of ​​the spring washer that is at the shortest distance from the outer ring, in particular the area in contact with the outer ring. This has the advantage that only a low material outlay is required, as only the contact areas between the spring washer and the outer ring and between the spring washer and the bearing cap need to be coated.

[0032] In an advantageous embodiment, the elastic washer is made of coated steel sheet. This has the advantage of providing a high modulus of elasticity. Therefore, the elastic washer can be manufactured cost-effectively and generates a high elastic force even with small axial deflections.

[0033] In an advantageous embodiment, the outer ring is arranged so as to be displaceable in the axial direction, in particular in the bearing receptacle, and / or the outer ring is connected to the bearing cover in a rotationally fixed manner by means of elastic washers. This has the advantage that, although the floating bearing is connected to the bearing cover in a rotationally fixed manner, in particular by a materially and / or force-fitting connection, the floating bearing is arranged so as to be axially displaceable in the event of thermally induced changes in the length of the rotor shaft.

[0034] In an advantageous embodiment, the elastic washer is in contact with both the outer ring and the bearing cap. Advantageously, the bearing preload is provided by means of the elastic washer and, due to the coating, a rotationally fixed connection between the outer ring and the bearing cap is provided.

[0035] In an advantageous embodiment, the bearing cover is connected to the stator housing of the electric motor.

[0036] The bearing flange is connected to the stator housing on the side of the stator housing axially facing away from the bearing cover.

[0037] The outer ring of the fixed bearing is accommodated in the bearing flange, and the inner ring of the fixed bearing is sleeved on the rotor shaft.

[0038] In particular, the inner ring of the fixed bearing rests on the shaft shoulder and is axially limited by a retaining ring arranged in an annular groove of the rotor shaft.

[0039] In particular, the outer ring of the fixed bearing rests axially on the bottom of the bearing receptacle of the bearing flange, on the one hand, and on the other hand, on a retaining ring arranged in an annular groove of the rotor shaft. This has the advantage that the stator housing undergoes thermally induced length changes due to the power loss of the stator winding, particularly in the axial direction. This length change of the stator housing differs from the length change of the rotor shaft, depending on the material and geometry. To compensate for this, the floating bearing is arranged to be movable in the axial direction.

[0040] In an advantageous embodiment, the rotor shaft passes through a recess in the bearing shield, and the fan is connected to the rotor shaft in a rotationally fixed manner on the side of the bearing shield facing away axially from the floating bearing.

[0041] To seal the notch, a shaft sealing ring is accommodated in the bearing cap, particularly in the notch of the bearing cap, and sealing is achieved towards the rotor shaft, particularly by contact of the sealing lip of the shaft sealing ring with the rotor shaft. This has the advantage that heat can be dissipated from the bearing cap by the airflow conveyed by the fan, thereby reducing changes in length.

[0042] In an advantageous embodiment, the rotor shaft passes through a hole through the bearing flange.

[0043] In this case, a further shaft sealing ring is received in a bore on the side of the fixed bearing facing away from the floating bearing, and sealing towards the rotor shaft is achieved, in particular by the contact of the sealing lip of the further shaft sealing ring with the rotor shaft. This has the advantage that the shaft sealing ring received in the bearing cap and the shaft sealing ring received in the bearing flange jointly seal the interior of the motor from the environment, and thus dirt or dust cannot penetrate into the bearing receptacle, which could impede or prevent the movement of the floating bearing.

[0044] In one advantageous embodiment, the stator laminated core with the stator winding is accommodated in a stator housing, and the squirrel-cage structure is mounted on the rotor shaft and connected to it in a rotationally fixed manner. This has the advantage that both the stator housing and the rotor shaft experience varying degrees of heat loss depending on the operating state of the motor. The resulting length changes can be compensated by the elastic washers according to the present invention.

[0045] Further advantages are provided by the dependent claims. The invention is not limited to the feature combinations of the claims. Other suitable combinations of the claims and / or features of individual claims and / or features of the description and / or features of the drawings will appear to a person skilled in the art, particularly based on the objectives presented and / or from a comparison with the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The invention is explained in more detail here with reference to the schematic diagram:

[0047] Figure 1 A cross-sectional view of an electric machine according to the present invention is shown.

[0048] Figure 2 An exploded oblique view of the bearing shield 3 of the electric machine with the elastic disk 2 and the floating bearing 1 is shown.

[0049] Figure 3 An oblique view of the elastic gasket 2 is shown.

[0050] Figure 4 A side view of the elastic spacer 2 is shown. DETAILED DESCRIPTION

[0051] As shown in the figure, the motor has a stator housing 9, which is connected to the bearing cover 3 at its first axial end region and to the bearing flange 8 at its other axial end region. That is, the stator housing 9 is axially arranged between the bearing flange 8 and the bearing cover 3.

[0052] A fixed bearing 7 is housed in the bearing cap 3. The inner ring of the fixed bearing is mounted on the rotor shaft 4 of the motor and abuts against a shoulder of the rotor shaft 4. The outer ring of the fixed bearing 7 is received in a bearing receptacle formed in the bearing flange 8 and is axially restrained by a retaining ring arranged in an annular groove of the bearing flange 8. Another retaining ring arranged in an annular groove of the rotor shaft 4 restrains the inner ring of the fixed bearing. Thus, the fixed bearing is axially fixed. Therefore, thermally induced expansion of the rotor shaft 4 must be compensated by the floating bearing 1.

[0053] The outer ring of the floating bearing 1 is accommodated in the bearing cover 3. The inner ring of the floating bearing 1 is placed on the rotor shaft 4 and rests on a shoulder formed on the rotor shaft 4 on the side of the floating bearing facing the fixed bearing.

[0054] The elastic disk 2 is arranged on the side of the floating bearing 1 facing away from the fixed bearing 7. In particular, the elastic disk 2 is arranged axially between the bottom of the bearing receptacle and the outer ring of the floating bearing 1.

[0055] The elastic washer 2, in particular a corrugated washer or even an elastically deformable and / or resilient corrugated washer, is embodied as an annular perforated washer, the annular axis of which is aligned coaxially with the rotational axis of the rotor shaft 4, and the edge region of which extends in a wavy manner in the circumferential direction, in particular wherein the amplitude of the wavy waves varies in the axial direction, i.e., the amplitude of the wavy waves or the axial position of the elastic washer 2 fluctuates, in particular, with increasing circumferential angle. This means, in particular, that the axial position of the elastic washer 2 is a periodic function of the circumferential angle.

[0056] When installed in the motor, the elastic disk 2 generates a bearing preload and is elastically deformed, ie, in particular, preloaded.

[0057] To this end, the elastic washer 2 is formed as a deformed stamped sheet metal part, specifically an annular steel sheet body. In particular, a perforated disk punched from the sheet metal is bent into a wave-like shape so that the axial position of the elastic washer 2 exhibits a periodic function as a function of the circumferential angular position relative to the rotational axis of the rotor shaft 4. In the circumferential direction, the period length is preferably 360° / N, where N is a natural number, particularly greater than 2. Consequently, the elastic washer has N maxima and N minima in the axial direction along its circumference. In particular, the maxima press against the outer ring of the floating bearing 1 in an elastically preloaded manner and thereby contact the outer ring, while the minima press against the bearing cover 3 in an elastically preloaded manner and thereby contact the bearing cover.

[0058] The rotation axis of the rotor shaft 4 is therefore aligned coaxially with the ring axis of the elastic disk 2 designed as a corrugated perforated disk.

[0059] The sheet material thickness, in particular the wall thickness, of the elastic gasket 2 is the same everywhere.

[0060] At the point of the elastic disk 2 at which the distance from the outer ring of the floating bearing 1 is greatest, ie in particular at the minimum, the elastic disk 2 is coated with adhesive 30 on its side facing away from the floating bearing 1 .

[0061] At the point of the elastic disk 2 at which the distance from the outer ring of the floating bearing 1 is smallest, ie in particular at the point of greatest distance, the elastic disk 2 is coated with adhesive 40 on its side facing the floating bearing 1 .

[0062] In this way, a material-locked connection is formed between the elastic washer 2 and the outer ring of the floating bearing 1, as well as between the elastic washer 2 and the bearing cover 3. Therefore, slipping of the elastic washer 2 or follow-up rotation of the outer ring of the floating bearing 1 is prevented.

[0063] Furthermore, the bearing receptacle is designed with a transition fit, so that the outer ring is seated in the bearing receptacle with only low static friction. This allows the outer ring of floating bearing 1 to move axially during thermal expansion of rotor shaft 4 without the outer ring tracking. This is because, despite the change in the elastic preload during axial displacement, the bearing preload is still provided by elastic disk 2.

[0064] In order to prevent the outer ring of the floating bearing 1 from following in the circumferential direction, the static friction torque provided in the bearing receptacle by means of a transition fit is smaller than a critical torque. When this critical torque is exceeded, the adhesive connection between the elastic washer 2 and the bearing cover 3 and / or the adhesive connection between the elastic washer 2 and the outer ring of the floating bearing 1 fails.

[0065] The fan 5 is connected to the rotor shaft 4 in a rotationally fixed manner on the side of the bearing cover 3 that is axially facing away from the fixed bearing 7. This achieves efficient passive heat dissipation.

[0066] The fan cover 6 surrounds the fan 5 and is connected to the bearing cover 3 .

[0067] A stator 10 , in particular a stator laminated core with a stator winding, is accommodated in a stator housing 9 .

[0068] In other exemplary embodiments according to the invention, a rubber layer or other coating is used instead of an adhesive, which produces sufficient static friction in the operative connection with the material of the bearing cap or the outer ring of the floating bearing 1 .

[0069] Here, in order to prevent the outer ring of the floating bearing 1 from following in the circumferential direction, the static friction torque provided in the bearing receptacle by means of a transition fit is smaller than the maximum static friction torque that can be provided by the friction fitting parts (i.e., the elastic washer 2, the bearing cover 3 and / or the outer ring of the floating bearing 1), especially in the circumferential direction.

[0070] In a further embodiment according to the invention, a carbide layer applied by means of a high-speed laser cladding welding method (HS-LMD) is used instead of the adhesive.

[0071] In other embodiments according to the present invention, the surface is roughened instead of being coated or bonded. This can be achieved by either sandblasting or laser structuring. While sandblasting is cost-effective, laser structuring not only produces isotropic elevations in the micrometer range to increase static friction, but also allows the creation of depressions and elevations that extend further radially than circumferentially. Because the laser-generated depressions and elevations extend further radially than circumferentially, a high static friction torque can be generated, i.e., a relative rotational movement of the elastic washer 2 relative to the corresponding friction pair (particularly the bearing cap 3 or the outer ring of the floating bearing 1).

[0072] In a refinement, one of the above-mentioned coatings can be applied to the rough surface.

[0073] List of reference numerals:

[0074] 1 Floating bearing

[0075] 2 elastic gaskets

[0076] 3 bearing cap

[0077] 4 Rotor shaft

[0078] 5. Fan

[0079] 6 Fan cover

[0080] 7 Fixed bearing

[0081] 8 Bearing flange

[0082] 9 Stator housing

[0083] 10 Stator, in particular a stator laminated core with stator winding

[0084] 30 adhesives

[0085] 40 Adhesive.

Claims

1. A motor, It has a rotor shaft, a floating bearing and a bearing cover, The floating bearing is provided for rotatably supporting the rotor shaft. The floating bearing has an inner ring and an outer ring, in particular, rolling elements are arranged between the inner ring and the outer ring. The outer ring of the floating bearing is received in a bearing receptacle formed in, in particular molded into, the bearing cover, in particular a cup-shaped bearing receptacle and / or in a blind hole. The inner ring is mounted on the rotor shaft. It is characterized by: The elastic washer, in particular the elastic corrugated washer, is arranged in the axial direction between the outer ring and the bearing cover, in particular the bottom of the bearing receiving portion. The elastic gasket has a coating on at least the first surface area and the second surface area, or is roughened by sandblasting or laser structured, in particular having ridges extending more in the radial direction than in the circumferential direction, In particular, the first surface areas are spaced apart from one another in the circumferential direction and the second surface areas are spaced apart from one another in the circumferential direction.

2. The motor according to claim 1, It is characterized by: The elastic disk rests both on the bearing cover, in particular on the bottom of the bearing receptacle, and on the outer ring.

3. An electric machine according to any one of the preceding claims, It is characterized by: The axial position of the elastic spacer, in particular the axial position of the median of the area covered by the elastic spacer in the axial direction, is a periodic function, in particular a non-zero function, of the circumferential angular position.

4. An electric machine according to any one of the preceding claims, It is characterized by: The outer ring is received in the bearing receiving portion in an interference fit manner.

5. An electric machine according to any one of the preceding claims, It is characterized by: The outer ring is received in the bearing receptacle with a precise fit, so that the static friction torque generated in the functional connection between the outer ring received in the bearing receptacle and the bearing cover is smaller than the static friction torque that can be generated by each or that functional connection with the outer ring by means of the elastic washer, and smaller than the static friction torque that can be generated by each or that functional connection with the bearing cover by means of the elastic washer.

6. An electric machine according to any one of the preceding claims, It is characterized by: The coating is an adhesive, a rubber layer and / or a plastic layer, or the coating comprises a metal layer, Alternatively, the coating comprises a carbide layer, in particular a metal carbide layer, in particular, the carbide layer, in particular the metal carbide layer is applied to a surface of the elastic gasket, in particular roughened by means of a laser, and / or the carbide layer, in particular the metal carbide layer is applied to the elastic gasket by means of a high-speed laser surface deposition welding process (HS-LMD).

7. An electric machine according to any one of the preceding claims, It is characterized by: The first surface area provided with the coating is the area of ​​the elastic washer that is furthest away from the outer ring.

8. An electric machine according to any one of the preceding claims, It is characterized by: The second surface area provided with the coating is the area of ​​the elastic washer that is shortest to the outer ring, in particular, the area in contact with the outer ring.

9. An electric machine according to any one of the preceding claims, It is characterized by: The elastic gasket is made of a steel plate to which a coating is applied.

10. An electric machine according to any one of the preceding claims, It is characterized by: The outer ring is arranged so as to be displaceable in the axial direction, in particular in the bearing receptacle, and / or is connected to the bearing cover in a rotationally fixed manner by means of elastic washers.

11. An electric machine according to any one of the preceding claims, It is characterized by: The elastic gasket contacts both the outer ring and the bearing cover.

12. An electric machine according to any one of the preceding claims, It is characterized by: The bearing cap is connected to the stator housing of the motor; The bearing flange is connected to the stator housing on a side of the stator housing axially facing away from the bearing cover; The outer ring of the fixed bearing is received in the bearing flange, and the inner ring of the fixed bearing is sleeved on the rotor shaft; In particular, the inner ring of the fixed bearing rests on the shaft shoulder and is axially limited by a retaining ring arranged in an annular groove of the rotor shaft; In particular, the outer ring of the fixed bearing bears axially on the one hand against the bottom of the bearing receptacle of the bearing flange and on the other hand against a retaining ring arranged in the annular groove of the rotor shaft.

13. An electric machine according to any one of the preceding claims, It is characterized by: The rotor shaft passes through a cutout of the bearing cover, and the fan is connected to the rotor shaft in a rotationally fixed manner on a side of the bearing cover that faces away axially from the floating bearing. To seal the recess, a shaft sealing ring is accommodated in the bearing cover, in particular in the recess of the bearing cover, and sealing towards the rotor shaft is achieved, in particular by the sealing lip of the shaft sealing ring being in contact with the rotor shaft.

14. An electric machine according to any one of the preceding claims, It is characterized by: The rotor shaft passes through a hole in the bearing flange. On the side of the fixed bearing axially facing away from the floating bearing, a further shaft sealing ring is received in the bore, and sealing towards the rotor shaft is achieved, in particular by the sealing lip of the further shaft sealing ring being in contact with the rotor shaft.

15. An electric machine according to any one of the preceding claims, It is characterized by: The stator laminated core with the stator winding is accommodated in the stator housing. The squirrel-cage structure is mounted on the rotor shaft and is connected to the rotor shaft in a rotationally fixed manner.

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