Electric machine

Abstract

Electrical machine with a housing (2), in particular a bearing shield, and a rotor (5) which is rotatable about a rotor axis (4) and which comprises a rotor shaft (6) which is rotatably mounted in at least one pivot bearing (8), in particular a rolling bearing, wherein the respective pivot bearing (8) is arranged between a housing seat (9) of the housing (2) and a shaft seat (10) of the rotor shaft (6) and has two bearing rings (8r), in particular an outer bearing ring (8ra) and an inner bearing ring (8ri), wherein at least one electrical bearing insulation (12) is provided on at least one pivot bearing (8) to prevent bearing currents, characterized in that the electrical bearing insulation (12) is provided between the shaft seat (10) and the bearing ring (8ri facing the shaft seat (10), in particular on the shaft seat (10).

Description

State of the art

[0001] The invention is based on an electrical machine according to the preamble of the main claim.

[0002] An electrical machine is already known from DE10037423 A1, comprising a housing, in particular a bearing shield, and a rotor rotatable about a rotor axis, which rotor comprises a rotor shaft rotatably mounted in at least one pivot bearing, in particular a rolling bearing. The respective pivot bearing is arranged between a housing seat of the housing and a shaft seat of the rotor shaft and has two bearing rings, in particular an outer bearing ring and an inner bearing ring. At least one electrical bearing insulation is provided on at least one pivot bearing to prevent bearing currents. The electrical bearing insulation is provided between the housing seat and the bearing ring facing the housing seat. The bearing insulation implemented on the housing seat can result in impaired cooling of the pivot bearing, since the bearing insulation can impair heat transfer to the housing.Due to the poor cooling of the pivot bearing, the pivot bearing can be damaged and in particular fail. Advantages of the invention

[0003] The electrical machine according to the invention with the characterizing features of the main claim has the advantage that the cooling of the rotary bearing provided with the electrical bearing insulation is improved.

[0004] This is achieved according to the invention in that the electrical bearing insulation is provided between the shaft seat and the bearing ring facing the shaft seat, in particular on the shaft seat and on the bearing seat.

[0005] The measures listed in the subclaims enable advantageous further developments and improvements of the electrical machine specified in the main claim.

[0006] According to an advantageous embodiment, the bearing insulation can comprise a ceramic layer or a plastic layer. The ceramic layer has the advantage of offering high temperature resistance, high mechanical strength, and low fatigue resistance over its service life. The plastic layer has the advantage of being easier to manufacture. Due to their position on the shaft seat, both designs are more effective and more cost-effective than commercially available bearing insulation, which is often located directly on the pivot bearing.

[0007] It is further advantageous if the bearing insulation comprises a thermally sprayed ceramic coating formed from oxide ceramic powder, in particular aluminum oxide (Al2O3), and / or aluminum nitride (AlN) powder, and produced in particular by high-pressure powder spraying (HVOF) or plasma spraying (APS). In this way, the bearing insulation has improved mechanical properties, in particular a particularly low tendency to relaxation. In addition, the bearing insulation thus exhibits very good media resistance. If exclusively aluminum nitride powder or a powder mixture containing aluminum nitride, which includes, for example, aluminum oxide and aluminum nitride, is used to produce the ceramic coating, the thermal conductivity of the bearing insulation can be increased compared to an oxide ceramic, in particular while maintaining the dielectric strength.

[0008] It is very advantageous if the bearing insulation comprises a sleeve-shaped insulation jacket layer for annularly enclosing the bearing ring and additionally an annular disk-shaped insulation collar layer for contact or support against a shaft-side bearing stop. In a variant of this solution, the bearing insulation can be achieved with separate insulation parts that are mounted on the rotor shaft. The layer thickness of the insulation jacket layer and the insulation collar layer can be easily varied, particularly in the solution with separate insulation parts, for example, depending on the respective application. High-frequency bearing currents are reliably avoided according to the invention if a minimum layer thickness is not exceeded at any point in the insulation jacket layer and / or the insulation collar layer.

[0009] According to the invention, the shaft-side bearing stop can be a shaft shoulder of the rotor shaft or a shaft ring mounted on the rotor shaft.

[0010] The shaft shoulder can be designed in two stages, with the annular disc-shaped insulation collar layer advantageously resting against or supported by the smaller-diameter shoulder of the two-stage shaft shoulder. This can increase the dielectric strength of the bearing insulation.

[0011] It is advantageous if the insulation collar layer extends radially beyond a radially outer edge of the bearing stop relative to the rotor axis. This can further increase the dielectric strength of the bearing insulation.

[0012] It is also advantageous if the insulation jacket layer and / or the insulation collar layer has a layer thickness that lies in the range between a minimum thickness and 1 mm, whereby the minimum thickness d (in millimeters) is calculated according to the formula d=ri⋅(1−e−εr⋅lb / 5300), where r i the inner radius of the pivot bearing relative to the rotor axis in mm, I b the axial length of the pivot bearing used in mm and ε r is the effective dielectric constant of the insulation material. This allows the layer thickness to be optimally designed for high electrical insulation against high-frequency bearing currents and at a low cost.

[0013] According to an advantageous embodiment, the insulation jacket layer and / or the insulation collar layer have a layer thickness in the range between 0.15 mm and 1 mm, in particular between 0.2 mm and 0.8 mm, especially between 0.3 mm and 0.8 mm. This layer thickness range represents the optimum between achievable electrical insulation effect against high-frequency bearing currents and achievable minimum costs.

[0014] According to an advantageous embodiment, the insulation jacket layer can be a coating of the shaft seat or part of a separate insulation component mounted on the rotor shaft. According to an advantageous embodiment, the insulation collar layer can be a coating of the shaft-side bearing stop or part of a separate insulation component mounted on the rotor shaft. This allows for very cost-effective variants of electrical bearing insulation.

[0015] According to a first variant, the separate insulating part can consist of an insulating material or, according to a second variant, can have a carrier body on which an insulating material is applied as a coating, in particular applied on one side or both sides.

[0016] The carrier body can be designed, for example, in the shape of a sleeve or a corrugated tube to form the insulation jacket layer and / or, for example, in the shape of a disc to form the insulation collar layer.

[0017] The insulation jacket layer and the insulation collar layer can be directly connected to one another or, alternatively, can be separate layers that are not directly connected to one another. In the case of a coating, the insulation jacket layer and the insulation collar layer can form a continuous or contiguous coating or two separate coatings. Alternatively, the insulation jacket layer and the insulation collar layer can together form a single insulation part or two separate insulation parts. One of the two layers can also be a coating and the other layer a separate insulation part.

[0018] It is also advantageous if the insulation jacket layer and the insulation collar layer have the same layer thickness. This can be useful if both layers are produced using the same coating process. Alternatively, the insulation jacket layer and the insulation collar layer can have different layer thicknesses. This can be useful if one of the two layers is a coating and the other layer is a separate insulation part. Both layers can also be formed as a coating with an initially equal layer thickness, with only the coating of the shaft seat subsequently being reworked to reduce the layer thickness.

[0019] Furthermore, it can advantageously be provided that the insulation jacket layer and the insulation collar layer are formed from the same insulation material or from different insulation materials.

[0020] It is also advantageous if the insulation jacket layer and / or the insulation collar layer have a pore structure with gas-filled, particularly air-filled, pores. Gaseous inclusions, preferably air, lead to a reduction in the effective permittivity of the insulation jacket layer and / or the insulation collar layer compared to a pore-free layer of the same layer thickness, thus increasing the electrical insulation effect against high-frequency bearing currents.

[0021] Additionally, it can advantageously be provided that the insulation jacket layer and / or the insulation collar layer is impregnated with an impregnating agent at least in sections, particularly on surfaces not covered by the bearing ring, to close pores and / or cracks in the insulation material of the bearing insulation. This prevents the dielectric strength of the bearing insulation from decreasing over the service life of the machine due to the incorporation of liquid media, such as water, in the pores and / or cracks, particularly microcracks.

[0022] It is further advantageous if the insulation jacket layer has at least one surface recess, which is particularly annular groove-shaped, or comprises several separate or not directly connected layers. Since this solution achieves a reduction in the effective permittivity of the insulation jacket layer and / or the insulation collar layer, the electrical insulation effect against high-frequency bearing currents is improved.

[0023] According to an advantageous embodiment, the shaft seat can have at least one surface recess, in particular an annular groove, which is covered by a bearing insulation coating, forming a corresponding surface recess in the insulation jacket layer. Since this solution also achieves a reduction in the effective permittivity of the insulation jacket layer and / or the insulation collar layer, the electrical insulation effect against high-frequency bearing currents is improved.

[0024] It is advantageous if the bearing insulation is provided on only one pivot bearing, particularly on the pivot bearing of the non-output side, in the case of a single output side of the machine, or on two pivot bearings in the case of two output sides of the machine. In this way, the particularly critical circular bearing currents that can propagate through the two pivot bearings of an electrical machine can be reduced to a level that is non-critical for the service life. At the same time, this arrangement protects the pivot bearings of the coupled transmission system from circular bearing currents. drawing

[0025] Embodiments of the invention are shown in simplified form in the drawing and explained in more detail in the following description.

[0026] They show: Fig. 1 an electrical machine with at least one rotary bearing on which an electrical bearing insulation according to the invention is provided, Fig. 2A a first variant of a bearing insulation according to the invention for the machine according to Fig. 1, Fig. 2B a second variant of a bearing insulation according to the invention for the machine according to Fig. 1, Fig. 2C a third variant of a bearing insulation according to the invention for the machine according to Fig. 1, Fig. 2D a fourth variant of a bearing insulation according to the invention for the machine according to Fig. 1, Fig. 2E a fifth variant of a bearing insulation according to the invention for the electrical machine according to Fig. 1, Fig. 2F a sixth variant of a bearing insulation according to the invention for the electrical machine according to Fig. 1, Fig. 2G a seventh variant of a bearing insulation according to the invention for the electrical machine according to Fig. 1, Fig. 2H an eighth variant of a bearing insulation according to the invention for the electrical machine according to Fig. 1 and Fig. 2I a ninth variant of a bearing insulation according to the invention for the electrical machine according to Fig. 1. Description of the embodiments

[0027] Fig. 1 shows an electrical machine with two pivot bearings, wherein an electrical bearing insulation according to the invention is provided on at least one of the pivot bearings.

[0028] The electric machine 1 has a housing 2, in particular a bearing plate, and a rotor 5 rotatable about a rotor axis 4, which includes a rotor shaft 6. The machine 1 naturally also has a stator 3, which, for example, encloses the rotor 5. The rotor shaft 6 of the rotor 5 is rotatably mounted in at least one pivot bearing 8, in particular a rolling bearing. The respective pivot bearing 8 is arranged between a housing seat 9 of the housing 2 and a shaft seat 10 of the rotor shaft 6 and has two bearing rings 8r, in particular a bearing outer ring 8ra and a bearing inner ring 8ri.

[0029] At least one electrical bearing insulation 12 is provided on at least one pivot bearing 8 to avoid so-called bearing currents.

[0030] The machine 1 has at least one output side 1a for transmitting the generated torque. The bearing insulation 12 is provided on only one pivot bearing 8, in particular on the pivot bearing 8 of the non-output side 1b, in the case of a single output side 1a of the machine 1, and on two pivot bearings 8 in the case of two output sides 1a of the machine 1.

[0031] Fig. 2A shows a first variant of a bearing insulation according to the invention for the machine according to Fig. 1.

[0032] According to the invention, the electrical bearing insulation 12 is provided between the shaft seat 10 and the bearing ring 8r facing the shaft seat 10, in particular on the shaft seat 10.

[0033] The electrical bearing insulation 12 can be a ceramic layer or a plastic layer. In the case of the ceramic layer, the bearing insulation 12 can be implemented as a thermally sprayed ceramic coating formed from oxide ceramic powder, in particular aluminum oxide (Al2O3), and / or aluminum nitride (AlN) powder, and produced in particular by high-pressure powder flame spraying (HVOF) or plasma spraying (APS).

[0034] The electrical bearing insulation 12 comprises a sleeve-shaped insulation jacket layer 12m for annularly enclosing the bearing ring 8r and additionally an annular disk-shaped insulation collar layer 12p for abutting or supporting on a shaft-side bearing stop 7. The shaft-side bearing stop 7 can be a shaft shoulder 6s of the rotor shaft 6 or a shaft ring 11 mounted on the rotor shaft 6.

[0035] The insulation jacket layer 12m and / or the insulation collar layer 12p can have a layer thickness d which lies in the range between a minimum thickness and 1mm, whereby the minimum thickness d (in mm) is calculated according to the formula d=ri⋅(1−e−εr⋅lb / 5300), where r i the inner radius of the pivot bearing 8 relative to the rotor axis 4 in mm, I b the axial length of the used pivot bearing 8 in mm and ε r is the effective dielectric constant of the insulation material of the bearing insulation 12.

[0036] According to one embodiment, the insulation jacket layer 12m and / or the insulation collar layer 12p can, for example, have a layer thickness d which is in the range between 0.15 mm and 1 mm, in particular between 0.2 mm and 0.8 mm, especially in particular between 0.3 mm and 0.8 mm.

[0037] The insulation jacket layer 12m and the insulation collar layer 12p can have the same or different layer thicknesses. Furthermore, the insulation jacket layer 12m and the insulation collar layer 12p can be made of the same insulation material or different insulation materials.

[0038] The insulation jacket layer 12m can be a coating of the shaft seat 10 or part of a separate insulation part mounted on the rotor shaft 6.

[0039] The insulation collar layer 12p can be a coating of the shaft-side bearing stop 7 or part of a separate insulation part mounted on the rotor shaft 6.

[0040] The insulation jacket layer 12m and the insulation collar layer 12p can be Fig. 2A can be directly connected to one another, in particular as a continuous coating or as a one-piece insulation part. In this case, the electrical bearing insulation 12 has an L-shaped cross-section.

[0041] Alternatively, the insulation jacket layer 12m and the insulation collar layer 12p can be Fig. 2B can be designed as separate layers, which are mounted, for example, as separate insulation parts on the rotor shaft 6. Between the insulation jacket layer 12m and the insulation collar layer 12p, Fig. 2C an axial distance can also be designed.

[0042] The separate insulation part or the separate insulation parts of the bearing insulation 12 can consist of an insulation material or can be made according to Fig. 2D, a carrier body 14 to which an insulating material is applied as a coating, in particular applied to one or both sides. The carrier body 14 can be sleeve-shaped or corrugated tube-shaped to form the insulating jacket layer 12m. To form the insulating collar layer 12p, the carrier body 14 can be disc-shaped.

[0043] After Fig. 2E, the insulation jacket layer 12 and / or the insulation collar layer 12p may have a pore structure with gas-filled, in particular air-filled, pores 15.

[0044] The insulation layer 12m can be Fig. 2F have at least one surface recess 16, in particular annular groove-shaped, or according to Fig. 2G comprise several separate layers.

[0045] The surface recess 16 of the insulation jacket layer 12m can be formed, for example, in that the shaft seat 10 has the corresponding surface recess 16, which is covered by a bearing insulation 12 designed as a coating, forming a corresponding surface recess in the insulation jacket layer 12m.

[0046] After Fig. 2I, the shaft shoulder 6s can be formed in two stages, wherein the annular disc-shaped insulation collar layer 12p rests against or is supported on the smaller-diameter shoulder of the two-stage shaft shoulder 6s. Furthermore, the insulation collar layer 12p can extend in the radial direction with respect to the rotor axis 4 with a projection 18 beyond a radially outer edge 17 of the bearing stop 7.

[0047] The insulation jacket layer 12m and / or the insulation collar layer 12p can be impregnated with an impregnating agent at least in sections, in particular on surfaces not covered by the bearing ring 8, to close pores and / or cracks in the insulation material of the bearing insulation 12. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This 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

[0000] DE 10037423 A1

[0002]

Claims

[1] Electrical machine with a housing (2), in particular a bearing shield, and a rotor (5) which is rotatable about a rotor axis (4) and which comprises a rotor shaft (6) which is rotatably mounted in at least one rotary bearing (8), in particular a rolling bearing, wherein the respective rotary bearing (8) is arranged between a housing seat (9) of the housing (2) and a shaft seat (10) of the rotor shaft (6) and has two bearing rings (8r), in particular a bearing outer ring (8ra) and a bearing inner ring (8ri), wherein at least one electrical bearing insulation (12) is provided on at least one rotary bearing (8) to avoid bearing currents, characterized by that the electrical bearing insulation (12) is provided between the shaft seat (10) and the bearing ring (8ri) facing the shaft seat (10), in particular on the shaft seat (10). [2] Machine according to claim 1, characterized by that the bearing insulation (12) comprises a ceramic layer or a plastic layer. [3] Machine according to one of the preceding claims, characterized by in that the bearing insulation (12) comprises a thermally sprayed ceramic coating formed from oxide ceramic powder, in particular aluminum oxide (Al2O3), and / or aluminum nitride (AlN) powder and is produced in particular by powder flame spraying (HVOF) or plasma spraying (APS). [4] Machine according to one of the preceding claims, characterized by that the bearing insulation (12) comprises a sleeve-shaped insulation jacket layer (12m) for annularly enclosing the bearing ring (8ri) and additionally an annular disc-shaped insulation collar layer (12p) for bearing against or supporting a shaft-side bearing stop (7). [5] Machine according to claim 4, characterized by that the shaft-side bearing stop (7) is a shaft shoulder (6s) of the rotor shaft (6) or a shaft ring (11) mounted on the rotor shaft (6). [6] Machine according to claim 5, characterized bythat the shaft shoulder (6s) is designed in two stages and the annular disc-shaped insulation collar layer (12p) rests against or is supported on the smaller diameter shoulder of the two-stage shaft shoulder (6s). [7] Machine according to one of claims 4 to 6, characterized by that the insulation collar layer (12p) extends in the radial direction with respect to the rotor axis (4) with a projection (18) beyond a radially outer edge of the bearing stop (7). [8] Machine according to one of claims 4 to 7, characterized by that the insulation jacket layer (12m) and / or the insulation collar layer (12p) has a layer thickness (d) which lies in the range between a minimum thickness and 1 mm, the minimum thickness being calculated according to the formula d=ri⋅(1−e−εr⋅lb / 5300), where r i the inner radius of the pivot bearing (8) relative to the rotor axis (4) in mm, I b the axial length of the rotary bearing used (8) in mm and εr is the effective dielectric constant of the insulation material. [9] Machine according to claim 8, characterized by that the insulation jacket layer (12m) and / or the insulation collar layer (12p) has a layer thickness (d) which is in the range between 0.15 mm and 1 mm, in particular between 0.2 mm and 0.8 mm, especially in particular between 0.3 mm and 0.8 mm. [10] Machine according to one of the preceding claims, characterized by , that - the insulation coating layer (12m) is a coating of the shaft seat (10) or part of a separate insulation part mounted on the rotor shaft (6), and / or - the insulation collar layer (12p) is a coating of the shaft-side bearing stop (7) or part of a separate insulation part mounted on the rotor shaft (6). [11] Machine according to claim 10, characterized bythat the separate insulation part consists of an insulation material or has a carrier body (14) on which an insulation material is applied as a coating, in particular applied on one side or both sides. [12] Machine according to claim 11, characterized by that the carrier body (14) is sleeve-shaped or corrugated tube-shaped to form the insulation jacket layer (12m) and / or disc-shaped to form the insulation collar layer (12p). [13] Machine according to one of the preceding claims, characterized by that the insulation jacket layer (12m) and the insulation collar layer (12p) are directly connected to one another, in particular as a continuous coating or as a one-piece insulation part, or are separate layers that are not directly connected to one another. [14] Machine according to one of the preceding claims, characterized by that the insulation jacket layer (12m) and the insulation collar layer (12p) - have the same layer thickness (d) or different layer thicknesses (d), and / or - are made of the same insulation material or of different insulation materials. [15] Machine according to one of the preceding claims, characterized by that the insulation jacket layer (12m) and / or the insulation collar layer (12p) has a pore structure with gas-filled, in particular air-filled, pores (15). [16] Machine according to one of the preceding claims, characterized by that the insulation jacket layer (12m) and / or the insulation collar layer (12p) is impregnated with an impregnating agent at least in sections, in particular on surfaces not covered by the bearing ring (8ri), for closing pores (15) and / or cracks in the insulation material of the bearing insulation (12). [17] Machine according to one of the preceding claims, characterized bythat the insulation jacket layer (12m) has at least one surface recess (16), in particular in the form of an annular groove, or comprises several layers separated from one another. [18] Machine according to one of the preceding claims, characterized by that the shaft seat (10) has at least one surface recess (16), in particular an annular groove, which is covered by a bearing insulation (12) designed as a coating, forming a corresponding surface recess (16) in the insulation jacket layer (12m). [19] Machine according to one of the preceding claims, characterized by that the bearing insulation (12) is provided on only one pivot bearing (8) in the case of a single output side (1a) of the machine, in particular on the pivot bearing of the non-output side (1b), or on two pivot bearings (8) in the case of two output sides (1a) of the machine (1).

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