Electric motor

Abstract

Electric motor (50) comprising a housing, a rotor (1) and a stator (16), wherein the rotor (1) has a shaft (66), the shaft (66) is mounted in the housing by a fixed bearing (11) and a loose bearing (44), wherein the floating bearing (44) is arranged to be axially movable and the shaft (66) has shaft sections with different diameters, whereby the transitions of the shaft sections form shaft diameter steps, wherein a spring element (41) is arranged axially between the floating bearing (44) and a housing part, in particular a bearing plate (42), wherein a ring of the floating bearing (44) is pressed by the spring element (41) against a shaft diameter step, wherein the spring element (41) is pressed against an outer ring of the floating bearing (42) and an inner ring of the floating bearing (42) is pressed against the shaft diameter step, wherein the spring element (41) is corrugated in the circumferential direction and is annular, wherein the spring element (41) forms a ring with a cloverleaf-shaped inner edge, in particular in axial plan view, and a corresponding outer edge, wherein the bearing plate (42) has, in the end face facing away from the stator housing (52), two grooves running around the passage of the shaft (66), wherein an annular circumferential lip (39) is formed on the fan wheel (36) around the fastening area (37) provided for attachment to the shaft (66), and the lip (39) is directed towards the bearing plate (42) and projects out to form a non-contact seal, wherein the lip (39) projects into one of the grooves of the bearing plate (42), an air gap being provided between the lip (39) and the groove, wherein the groove is deeper than an axial distance between a bearing shield-side end face of the floating bearing (44) and a support surface of the spring element on the bearing shield (42), wherein the remaining opening of the passage of the bearing plate (42) is sealed by a shaft seal (30), wherein an axial receiving area of ​​the shaft sealing ring (30) in the bearing plate (42) is longer in the axial direction than a depth of the grooves in the bearing plate (42), wherein a fan cover (35) is placed at least partially overlapping onto the bearing plate (42), wherein the fan cover (35) has the shape of an approximately square shell with rounded corners and a flat bottom, wherein L-shaped recesses are arranged in wall sections of the rounded corners on the stator housing side, which are surrounded by further C-shaped recesses.

Description

[0001] The invention relates to an electric motor.

[0002] It is common knowledge that an electric motor that has a shaft supports this shaft with two bearings.

[0003] From DE 10 2004 063 920 A1, a series of electric motors is known as the closest state of the art.

[0004] A bearing arrangement for a small electric motor is known from DE 198 43 226 A1.

[0005] An electrical machine is known from WO 2004 / 107 533 A1.

[0006] A bearing shield for three-phase motors is known from DE 78 24 654 U1.

[0007] An electric motor with a fan and fan cover is known from DE 10 2005 016 905 B3.

[0008] An electric motor with a terminal box is known from DE 10 2004 027 653 A1.

[0009] An electric motor with a fan and fan cover is known from DE 10 2005 054 251 A1.

[0010] A fan cover is known from DE 10 2005 045 487 A1.

[0011] From DE 102 38 336 A1 a series of motors is known, each of which also includes a motor housing with molded ribs and a terminal box.

[0012] A low-noise small electric motor with a ball-bearing shaft is known from DE 12 07 482 A.

[0013] A clutch motor is known from DE 83 16 122 U1.

[0014] An electric motor is known from DE 10 2005 053 548 A1.

[0015] The invention is therefore based on the object of developing an electric motor, wherein the service life of the electric motor is increased.

[0016] According to the invention, the object is achieved in the electric motor according to the features specified in claim 1.

[0017] Important features of the invention in the electric motor are that it comprises a housing, a rotor and a stator, wherein the rotor has a shaft, the shaft is mounted in the housing by a fixed bearing and a loose bearing, wherein the loose bearing is arranged to be axially movable and the shaft has shaft sections with different diameters, whereby the transitions of the shaft sections form shaft diameter steps, wherein a spring element is arranged axially between the floating bearing and a housing part, in particular a bearing shield, wherein a ring of the floating bearing is pressed by the spring element against a shaft diameter step.

[0018] The advantage here is that the floating bearing is held firmly on the shaft. This reduces the risk of the floating bearing slipping off the shaft or becoming jammed, resulting in premature wear, and increases the service life of the electric motor. The well-defined position of the floating bearing also leads to well-defined and reliable heat transfer from the shaft via the bearing to the housing.

[0019] In an advantageous embodiment, the contact force generated by the spring element is smaller than the maximum axial force that the bearing can absorb. This is advantageous in that the bearing is not overloaded in the axial direction, bearing wear is reduced, and a well-defined heat transfer from the shaft to the housing is ensured.

[0020] According to the invention, the spring element is pressed against an outer ring of the floating bearing, and an inner ring of the floating bearing is pressed against the shaft diameter step. The advantage here is that the spring element has the same outer diameter as the floating bearing and can be held more securely in the bearing recess of the floating bearing. This simplifies the assembly and production of the electric motor and ensures better heat transfer from the shaft via the bearing and the shim to the housing.

[0021] According to the invention, the spring element is corrugated, in particular corrugated in the circumferential direction, and / or annular. Advantageously, the spring element is a single piece and easy to manufacture, and the spring force can be adjusted by the height and / or number of corrugations and / or the material used, providing improved heat transfer from the shaft to the housing.

[0022] According to the invention, the spring element forms a ring with a cloverleaf-shaped inner edge, particularly in axial plan view, and a corresponding outer edge. The advantage here is that the spring element is easy to handle during assembly and can be safely and easily mounted in the electric motor. The secure, well-defined assembly also improves heat transfer.

[0023] In a further advantageous embodiment, the bearing plate has a shaft bushing that runs through a thickened area of ​​the bearing plate. The advantage here is that the thickened area provides greater stability for the shaft bearing and has greater thermal capacity and conductivity.

[0024] In a further advantageous embodiment, the thickened area is shaped toward the interior of the housing. This allows the electric motor to be manufactured in a more compact design and allows for better heat dissipation.

[0025] In a further advantageous embodiment, the end shield has stiffening struts on the side facing into the housing, extending radially from the thickened area to a periphery of the end shield. The advantage of this is that the electric motor has greater rigidity while using less material. At the same time, heat dissipation is also improved.

[0026] In a further advantageous embodiment, a hollow cylinder with a larger diameter than the shaft bushing, completely open to the interior of the housing, is arranged centered around the shaft bushing in the thickened area, and this hollow cylinder serves as a bearing support for the floating bearing. The advantage here is that the floating bearing and the spring element can be easily and precisely mounted, and the well-defined position improves heat transfer.

[0027] In a further advantageous embodiment, the bearing plate has a groove on the end face facing away from the stator housing, which runs around the shaft passage. This is advantageous in that the surface area of ​​the bearing plate is enlarged, thereby improving heat radiation and thus heat transfer from the shaft to the housing.

[0028] In a further advantageous embodiment, the housing comprises a stator housing with cooling fins arranged parallel to one another and extending approximately radially from the stator housing. The advantage here is that the cooling fins provide better heat radiation and thus improve the heat transfer from the shaft to the housing.

[0029] In a further advantageous embodiment, the free ends of the cooling fins rest on a flat support surface, in particular four flat support surfaces arranged approximately at right angles to one another. The advantage here is that the flat support surfaces provide a geometrically more advantageous support surface onto which additional heat sinks can be easily applied or placed, thereby lowering the housing temperature and thus improving heat transfer from the shaft to the housing.

[0030] In a further advantageous embodiment, the housing has a terminal box. This has the advantage that the surface area of ​​the housing is enlarged, thus improving heat radiation from the housing, which improves heat transfer from the shaft to the housing.

[0031] In a further advantageous embodiment, the terminal box comprises a terminal box base and a terminal box cover, a seal for the terminal box cover, which is clamped between the terminal box cover and the terminal box base, and a seal for the terminal box base, which is clamped between the terminal box base and a terminal box base molded onto the housing. The advantage here is that the surface area of ​​the housing is enlarged, thus improving heat radiation from the housing, which improves heat transfer from the shaft to the housing.

[0032] In a further advantageous embodiment, a terminal plate is mounted in the terminal box base. The terminal plate has at least one threaded rod with a screw nut and a washer that can be screwed onto the threaded rod. The advantage of this is that the surface area of ​​the housing is enlarged, thus improving heat dissipation from the housing, which improves heat transfer from the shaft to the housing.

[0033] In a further advantageous embodiment, various clamping devices are arranged in the terminal box base. The advantage of this is that the surface area of ​​the housing is enlarged, thus improving heat dissipation, which improves heat transfer from the shaft to the housing.

[0034] In a further advantageous embodiment, cable ducts are arranged in one wall of the terminal box base, which can be closed with locking screws and an appropriately sized O-ring. This has the advantage of protecting the terminal box from contamination.

[0035] According to the invention, a fan cover is placed at least partially overlapping the bearing plate. The advantage of this is that the surface area of ​​the housing is enlarged, thus improving heat dissipation, which improves heat transfer from the shaft to the housing.

[0036] According to the invention, the fan cover has the shape of an approximately square shell with rounded corners and a flat bottom. This has the advantage of increasing the surface area of ​​the housing, thus improving heat dissipation and heat transfer from the shaft to the housing.

[0037] In a further advantageous embodiment, the base is formed by a grid structure. This allows air to flow to the bearing shield, allowing for better heat dissipation and improving heat transfer from the shaft to the housing.

[0038] In a further advantageous embodiment, a circumferential wall of the fan cover has a first section parallel to the axial direction of the shaft and a second section extending inward in a funnel shape at an angle to the axial direction of the shaft. The advantage of this is that the surface area of ​​the housing is enlarged, thus improving heat radiation from the housing, which improves heat transfer from the shaft to the housing.

[0039] In a further advantageous embodiment, the first section toward the housing has a corresponding circumference suitable for partially overlapping the bearing plate, which tapers off toward the bottom of the fan cover. The advantage here is that the partially overlapping fit ensures good heat conduction between the housing and the fan cover, thus improving heat dissipation and heat transfer from the shaft to the housing.

[0040] According to the invention, L-shaped recesses are arranged in the wall sections of the rounded corners on the stator housing side, which are surrounded by further C-shaped recesses. The advantage of this is that the fan cover is securely and precisely pushed and secured onto the bearing plate, thus ensuring good heat conduction, which improves heat transfer from the shaft to the housing. The C-shaped recesses also reduce the transmission of vibrations from the housing to the fan cover.

[0041] In a further advantageous embodiment, a fan impeller is connected to the shaft in a rotationally fixed manner, in particular by a positive connection. The advantage here is that the fan reliably cools the housing while the electric motor is running and reduces the housing temperature, thereby improving heat transfer from the shaft to the housing.

[0042] In a further advantageous embodiment, the fan impeller is arranged outside the housing, axially following the bearing plate. This provides the advantage of a compact electric motor design and generating the airflow close to the housing to effectively cool the housing, thus improving heat transfer from the shaft to the housing due to a lower housing temperature.

[0043] In a further advantageous embodiment, the fan wheel has a radially projecting fan disk forming a truncated cone with its base open toward the bearing plate. This is advantageous in that the generated air flow is effectively directed to the housing to effectively cool the housing, thus improving heat transfer from the shaft to the housing.

[0044] In a further advantageous embodiment, the fan disc transitions radially toward the shaft into a U-shaped mounting area for the fan wheel, and an innermost edge of the mounting area forms the inner casing of a fan wheel cylinder that is in contact with the shaft. The advantage here is that the fan wheel is securely mounted on the shaft, thus generating a well-defined and reliable airflow to the housing to effectively cool the housing and thus improve heat transfer from the shaft to the housing.

[0045] In a further advantageous embodiment, the shaft-side leg of the U of the mounting area is fixed by the additional shaft diameter step of the shaft and the additional retaining ring. This is advantageous in that the fan wheel is securely mounted on the shaft and thus generates a well-defined and reliable airflow to the housing to effectively cool the housing and thus improve heat transfer from the shaft to the housing.

[0046] In a further advantageous embodiment, the fan wheel has at least one fan blade positioned approximately perpendicular to the fan disk. This has the advantage of generating an air flow to the housing to cool the housing, thus improving heat transfer from the shaft to the housing.

[0047] According to the invention, an annular lip is formed on the fan impeller around the mounting area, and the lip is directed toward the bearing shield, in particular protruding, to form a non-contact sealing area. The advantage of this is that the shaft passage in the bearing shield is additionally protected from contamination, thus protecting the bearing and the spring element from contamination, reducing wear, and improving heat transfer from the shaft to the housing.

[0048] According to the invention, the lip extends into the groove of the bearing shield, with an air gap provided between the lip and the groove. This provides additional protection for the shaft passage in the bearing shield, thus protecting the bearing and spring element from contamination, reducing wear, and improving heat transfer from the shaft to the housing. If the electric motor is installed in a suitable location, the shaft seal in the bearing shield can be omitted.

[0049] In a further advantageous embodiment, the groove is deeper than a range of length changes that can be compensated for by the axially movable arrangement of the floating bearing, particularly within the operating temperature range. The advantage here is that the lip can extend far enough into the groove that the sealing function of the lip in interaction with the groove is maintained during any length change of the shaft.

[0050] According to the invention, the groove is deeper than the axial distance between a bearing-shield-side end face of the floating bearing and a support surface of the spring element on the bearing shield. The advantage here is that the lip can extend far enough into the groove to ensure the sealing function of the lip in conjunction with the groove during any change in shaft length.

[0051] In a further advantageous embodiment, the fan wheel is molded in one piece from plastic or aluminum. This allows for a low moment of inertia and thus high dynamics when approaching a position.

[0052] Further advantages emerge from the dependent claims. The invention is not limited to the combination of features in the claims. Further possible combinations of claims and / or individual claim features and / or features of the description and / or the figures will become apparent to those skilled in the art, particularly from the problem and / or the problem posed by comparison with the prior art.

[0053] The invention will now be explained in more detail with the aid of illustrations: In the Fig. 1 shows a perspective view of an electric motor 50 according to the invention. The electric motor 50 has an approximately cylindrical stator housing 52 with cooling fins 54 arranged parallel to one another and projecting approximately radially from the stator housing. The free ends of the cooling fins 54 lie in a flat support surface, in particular in four flat support surfaces arranged approximately at right angles to one another. Trapezoidal beads 55 on the end regions of the outer surfaces of the stator housing 52 form corner elements between the flat support surfaces. In at least one of the flat support surfaces, blind-hole-like fastening bores 60 with internal threads are formed in four almond-shaped thickenings 58 of the cooling fins 54. These serve as fastening options for various add-on elements, such as a base plate 90, which in turn serves to fasten the electric motor 50 in various positions.

[0054] A cuboid-shaped terminal box 110 is screwed to a terminal box base 56 provided for this purpose. The terminal box base 56 is formed integrally with the stator housing 52 and protrudes along the cooling fins 54 in an approximately radial direction beyond the free ends of the cooling fins 54. The terminal box 110 has a terminal box base 112 and a terminal box cover 132, which is screwed to the terminal box base 112 with a hexagon screw 123.

[0055] The end faces of the stator housing 52 are closed by additional housing parts, such as a bearing plate 42 and a flange plate 64—except for a passage for a shaft 66 in the flange plate 64 and a shaft passage in the bearing plate 42. A flange 7 for flanging driven devices is formed onto the flange plate 64. For this purpose, the flange 7 has a flange bore 70.

[0056] A cylinder head screw 13 is guided through holes in the bearing plate 42 and holes in the trapezoidal bulge on the stator housing 52 and screwed into an internal thread of a hole in a trapezoidal bulge on the flange plate 64. Thus, the flange plate 64 and the bearing plate 42 are pressed against the end faces of the stator housing 52 in a rotationally fixed manner. A housing of the electric motor 50 comprises the flange plate 64, the bearing plate 42, and the stator housing 52.

[0057] A fan cover 35 is placed on the circumference of the bearing plate 42, or is slipped over it in the axial direction, partially overlapping the bearing plate 42, and is fastened to the bearing plate 42 with further hexagon screws 22.

[0058] Fig. 2 shows the Fig. 1 shows an exploded perspective view of the electric motor 50 according to the invention, wherein the flange plate 62 is designed as a transmission flange and the electric motor 50 is additionally provided with a protective roof 705.

[0059] The rotor 1 has a shaft 66 and a rotor core 72, which is non-rotatably mounted on the shaft 66, in particular by force-locking. The shaft 66 has several shaft sections with different diameters in the axial direction. The transitions between the shaft sections form several shaft diameter steps due to the different diameters. The rotor core 72 is arranged non-rotatably approximately centrally on the shaft 66 in the shaft section with the largest shaft diameter, in particular, it is pressed onto this shaft section.

[0060] A fixed bearing 11, designed as a deep groove ball bearing, is pushed onto the shaft 66 on the flange shield side, and an inner ring of the fixed bearing 11 is axially fixedly mounted on the shaft side by a retaining ring 10 and a shaft diameter step. On the bearing shield side, a loose bearing 44, designed as a deep groove ball bearing, is pushed onto the shaft 66 up to a further shaft diameter step. A spring element 41 is designed as an annular spring element and, when viewed from the axial direction, has an approximately cloverleaf-shaped inner edge and a corresponding outer edge. Cloverleaf-shaped here means the outline of a four-leaf clover without a stem, or in other words, a circle that is symmetrically dented inwards at four points. To generate the spring effect, the spring element 41 is shaped so as to be corrugated, for example, in the circumferential direction.The floating bearing 44 is fixed between the additional shaft diameter step and the spring element 41 in a bearing mount in the bearing plate 42, allowing it to move axially. This is movable in the sense that the floating bearing 44 can follow axial displacements of the additional shaft diameter step due to a change in the length of the shaft 66, since the spring element 41 provides corresponding spring action without deforming the floating bearing 44 or adversely changing the bearing properties. In this way, for example, thermally induced changes in the length of the shaft 66 or manufacturing tolerances of the shaft 66 and the bearing mount are accommodated.

[0061] In an end section of the shaft 66 on the bearing shield side, a fan wheel 36 is mounted on the shaft 66 in a rotationally fixed manner, in particular in a form-fitting manner, such as with a flattened portion 5 in the shaft cross-section or a fan wheel key. In the axial direction, the fan wheel 36 is fixed by an additional shaft diameter step and a further retaining ring 32 and / or by a force-fitting manner.

[0062] An interior of the housing is protected from contaminants such as dust, water, and / or gear oil by a splash washer 107 and a shaft seal 106 in the passage for the shaft 66 in the flange plate 64. A driven device can be flange-mounted to the flange 7 using stud bolts 103 and hexagon nuts 100. A rotating part of this driven device can be non-rotatably attached to the shaft 66, in particular by means of the key 3.

[0063] A screw plug 9 serves to close an oil inlet opening. If a gearbox is directly flanged to flange 7, the gearbox oil can be supplied or replaced via this oil inlet opening.

[0064] The fixed bearing 11 is fixed on the stator housing side by the flange plate 64 and a retaining ring for bores 12.

[0065] A stator 16 has a stator core 18 and a stator winding 20 with a winding head 21 and is mounted in the stator housing 52. The base plate 90 is attached to the stator housing 52 with screws 93.

[0066] A terminal plate 115 is attached to the terminal box base 56 by means of another screw 113. The terminal plate 115 has at least one threaded rod designed as a terminal bolt with a screw nut and a washer that can be screwed onto the threaded rod. In the stator housing 52, in the area of ​​the terminal box base 56, there are cable bushings for intended connecting cables, such as connecting cables for the stator winding 20. The four inner corners of the terminal box base 56 are reinforced in an approximately cylindrical shape. These reinforcements contain blind holes with internal threads. A seal 111 for the terminal box base 112 is clamped between the terminal box base 112 and the terminal box base 56. The terminal box base 112 is screwed to the terminal box base 56 by means of fastening screws 119.Located in one wall of the terminal box base 112 are cable glands of various sizes, which can be sealed with appropriately sized O-ring plugs 129, 134. The end portion of the terminal box base 112 facing the stator housing 52 is formed as a circumferential, flattened, rectangular ring, approximately identical in shape to an end face of the terminal box base 56. Various clamping devices are located on this ring, projecting into the interior of the terminal box base 112.

[0067] The terminal plate 115 and the various clamping devices can be used for the electrical connection of external cables supplied from the outside with the cables supplied from the electric motor 50 into the terminal box 110, such as the cables leading from the stator winding 20. The clamping devices are designed, for example, as a connecting terminal 262 or as a clamping device with a clamping screw 117, a spring washer 118, and at least one clamping bracket 116. In the latter example, the clamping screw 117 is screwed into a cuboid-shaped elevation provided for this purpose on the ring of the terminal box base 112. An information plate 156 is arranged inside the terminal box 110. The terminal box 110 is closed with a terminal box cover 132 and a seal 131 for the terminal box cover 132, which is clamped between the terminal box cover 132 and the terminal box base 112.For this purpose, the terminal box cover 132 is screwed to the terminal box base 112 with the hexagon screws 123.

[0068] A rating plate 108 is attached to a flat support surface by means of a grooved nail 109. The rating plate 108 bears the technically relevant parameters and the product designation for the electric motor 50.

[0069] A housing seal 392 is arranged between the bearing plate 42 and the stator housing 52. This seal is held in a rotationally fixed manner by the cylinder head screws 13 via corresponding holes in the housing seal 392 and is clamped between the bearing plate 42 and the stator housing 52 in the assembled state. The shaft seal 30 closes the remaining opening of the feedthrough in the bearing plate 42 when the shaft 66 is installed in order to protect the interior of the stator housing 52 from contaminants such as dust or water.

[0070] For stiffening purposes, the bearing shield 42 has radially outward-running struts on the side facing the stator housing 52. The bearing shield 42 forms a thickened portion in the area of ​​the shaft feedthrough. The thickened portion is shaped towards the stator housing 52. A hollow cylinder in the thickened portion of the bearing shield 42, which is completely open towards the stator housing, is shaped more concentrically to the shaft feedthrough with a larger diameter than the shaft feedthrough and forms a cylindrical bearing seat for the floating bearing 44. Since an outer ring and the inner ring of the fixed bearing 11 are axially fixed, the floating bearing 44 does not have to absorb any axial forces acting on the shaft 66 from the outside. A thickened outer edge of the bearing shield 42 is also shaped towards the stator housing 52 and has further cooling fins on its outer edge, which are at least partially designed as a continuation of the cooling fins 54 of the stator housing 52.Also formed on the outer edge of the bearing plate 42 is a thickened portion, which has a through-hole aligned parallel to the shaft 66 and a blind hole with an internal thread arranged perpendicularly thereto and running radially to the shaft 66. The through-hole serves to accommodate the cylinder head screw 13, and the blind hole with an internal thread running radially to the shaft 66 serves to fasten the additional hexagon screws 22.

[0071] In the assembled state, the fan wheel 36 is arranged between the bearing plate 42 and the grid structure of the fan cover 35 and is enclosed by the fan cover 35.

[0072] The fan cover 35 has the shape of an approximately square shell with rounded corners and a flat base, wherein the base is not closed but formed by a lattice structure. The fan cover 35 is pushed onto the bearing plate 42 with the opening facing the bearing plate 42, so that the lattice structure of the fan cover runs approximately parallel to the bearing plate 42. A circumferential wall of the fan cover 35 has a first section parallel to the axial direction of the shaft 66 and a second section extending inwards in a funnel shape at an angle to the axial direction of the shaft 66. On the stator housing side, the first section has a corresponding circumference suitable for partially overlapping slipping onto the bearing plate 42, which decreases by a step towards the base of the fan cover 35.In wall sections of the rounded corners, L-shaped recesses are arranged on the stator housing side, allowing the fan cover 35 to be snapped into the additional hexagon screws 22 screwed to the bearing plate 42 and then, by finally tightening the additional hexagon screws 22, to fasten the fan cover 35 to the bearing plate 42. Additional C-shaped recesses run around the L-shaped recesses and reduce the transmission of vibrations from the electric motor 50 to the fan cover 35.

[0073] The second section of the fan cover 35 has approximately wave-shaped elevations and depressions in the sections which, in the assembled state, are designed as a continuation of the flat support surfaces of the stator housing 52.

[0074] A plate-shaped protective cover 705 is arranged to cover the grid structure of the fan cover 35. A spacer 706 is arranged between the protective cover 705 and the fan cover 35 and ensures that sufficient air can flow through the grid structure to the fan impeller 36. The protective cover 705 and the spacer 706 have through-holes through which a protective cover screw 707 is passed. In the assembled state, the protective cover screw 707 is screwed tightly into threads arranged on the fan cover 35. Thus, the protective cover 705 and the spacer 706 are fastened to the fan cover 35. A further key 4 on a fan-side end region of the shaft 66 serves for the rotationally fixed, positive connection of additional devices to the shaft 66.

[0075] Fig. 3 shows the Fig. 1 shows the electric motor 50 according to the invention in a longitudinal section.

[0076] The flange plate 64 and the bearing plate 42, together with the stator housing 52, enclose an approximately cylindrical interior of the housing of the electric motor 50. The shaft 66 is mounted opposite the housing by the fixed bearing 11 and the floating bearing 44. The fixed bearing 11 is arranged in a fixed bearing holder formed in the flange plate 64 and is held on the shaft side by the shaft diameter step and the retaining ring 10. The retaining ring 10 is snapped into an annular groove in the shaft 66. On the housing side, the fixed bearing 11 is held by an annularly circumferential corner of the fixed bearing holder and by the retaining ring for a bore 12. The retaining ring for a bore 12 is snapped into a groove in the fixed bearing holder in the flange plate 64. The remaining opening of the feedthrough for a shaft in the flange plate 64 is sealed by the shaft sealing ring 106.

[0077] The stator 16 with the stator windings 20 with winding head 21 and the stator laminated core 18 is fixed in the stator housing 52 by fastening means 80, in particular pressed into the stator housing 52. The rotor core 72 pressed onto the shaft 66 has a rotor laminated core 74. Laminates of the rotor laminated core 74 are connected to one another, for example by stamping and / or by a rotor casting 76 forming a squirrel cage of the rotor 1. The rotor casting penetrates recesses in the laminated cores and, forming an annular bead, protrudes beyond the rotor laminated core 74 on both sides in the axial direction of the shaft 66.

[0078] The floating bearing 44 is arranged in the cylindrical bearing mount. Because the inner ring of the floating bearing 44 rests with its stator housing-side end face against a radial surface of a further shaft diameter step, the floating bearing 44 is supported on the shaft side towards the rotor core 72. The spring element 41 is arranged between the floating bearing 44 and the bearing shield 42 in the cylindrical bearing mount and is supported on a support surface in the bearing shield. An outer ring diameter of the spring element 41 is larger than a diameter of the shaft feedthrough and less than or equal to a diameter of the cylindrical bearing mount. An inner opening diameter of the annular spring element 41 is at least as large as the shaft diameter of the shaft 66 in the area of ​​the cylindrical bearing mount.Due to the special, circumferentially undulating shape of the annular spring element 41, the spring element 41 does not contact the end face of an outer ring of the floating bearing 44 on the bearing shield side all the way around, but at least in one section. On the bearing shield side, the spring element 41 contacts the bearing shield 42 at least in one other section of the support surface. This support surface only has to absorb a spring force from the spring element 41 in the axial direction. For example, in the special design as a cloverleaf-shaped spring element 41, the inwardly drawn areas with a smaller outer diameter contact the bearing shield 42, and the outwardly drawn areas with the maximum outer diameter of the shim 41 contact the outer ring of the floating bearing 41.When the shaft 66 changes axially in length, the floating bearing 44 follows the movement of the shaft diameter step and the inner ring of the floating bearing 44 remains pressed against the radial surface of the shaft diameter step due to the spring force of the spring element 41.

[0079] In an alternative embodiment, the spring element presses against the inner ring of the floating bearing 44. In this case, the fixed bearing and the floating bearing are fixed in the electric motor without stress. In another alternative embodiment, the spring element presses against the inner ring and the outer ring.

[0080] The shape and material of the spring element 41 are selected such that, over the service life of the electric motor 50, the floating bearing 44 is axially movably fixed by the spring element 41 during many length change cycles of the shaft 66, i.e., expansion and contraction in the axial direction. The pressing force of the compensating disc 41, taking manufacturing tolerances into account, is smaller than the maximum axial force that the floating bearing 44 can absorb. In particular, the pressing force is adjustable by the number and / or shape of a rotating shaft of the annular spring element 41. Suitable materials for the spring element include metal, particularly spring steel, which is also suitable for heat transfer between the bearing and the housing.

[0081] The end face of the bearing plate 42 facing away from the stator housing 52 has two grooves surrounding the passage of the shaft 66. The remaining opening of the passage of the bearing plate 42 is sealed by the shaft seal 30. An axial receiving area of ​​the shaft seal 30 in the bearing plate 42 is longer in the axial direction than the depth of the grooves in the bearing plate 42. The heat of the shaft seal 30 is dissipated past the grooves and further transported radially outward via the bearing plate 42 and the radially extending struts in the bearing plate 42.

[0082] Approximately close to the bearing plate 42, the fan wheel 36 is non-rotatably mounted on the shaft 66. The fan wheel 36 is axially secured by the additional shaft diameter step in the shaft 66 and the additional retaining ring 32. The fan wheel 36 has a radially projecting fan disc forming a truncated cone with its base open toward the bearing plate (42).

[0083] A radially extending fan blade 38 is positioned approximately perpendicular to the fan disk on the side of the fan disk facing away from the housing. The fan disk transitions radially toward the shaft 66 into a U-shaped mounting area 37 of the fan wheel 36. An innermost edge of the mounting area 37 forms the inner shell of a fan wheel cylinder that is in contact with the shaft 66. The shaft-side leg of the U of the mounting area is clamped by the further shaft diameter step of the shaft 66 and the further retaining ring 32. The fan wheel 36 is thus secured in the axial direction.

[0084] A sealing area forming two lips 39 is formed around the fastening area 37. The two lips 39 are directed towards the bearing plate 42 and engage in the grooves of the bearing plate 42 so as to be rotatable relative to the latter. An air gap is present between the lip and the groove. The fact that the fan wheel 36 is arranged with respect to the bearing plate 42, or at least one lip with respect to a groove, such that the lip overlaps the groove, provides additional protection against contamination for the passage of the shaft 66 in the bearing plate 42. This is ensured for all operating conditions of the electric motor 50. If the working environment of the electric motor is suitable, the shaft sealing ring 30 can be omitted. The fan cover 35 is slipped over the fan wheel 36 and the bearing plate 42. The fan wheel 36 is preferably molded in one piece from a lightweight material such as plastic.

[0085] The fan cover 35 has a passage for the shaft 66. This allows a driven device to be mounted on the fan cover side.

[0086] Blind holes in the end faces of the shaft 66 and a snap ring 2 serve as additional centering and / or fastening options for various elements to be driven.

Claims

[1] Electric motor (50) comprising a housing, a rotor (1) and a stator (16), wherein the rotor (1) has a shaft (66), the shaft (66) is mounted in the housing by a fixed bearing (11) and a loose bearing (44), wherein the floating bearing (44) is arranged to be axially movable and the shaft (66) has shaft sections with different diameters, whereby the transitions of the shaft sections form shaft diameter steps, wherein a spring element (41) is arranged axially between the floating bearing (44) and a housing part, in particular a bearing plate (42), wherein a ring of the floating bearing (44) is pressed by the spring element (41) against a shaft diameter step, wherein the spring element (41) is pressed against an outer ring of the floating bearing (42) and an inner ring of the floating bearing (42) is pressed against the shaft diameter step, wherein the spring element (41) is corrugated in the circumferential direction and is annular, wherein the spring element (41) forms a ring with a cloverleaf-shaped inner edge, in particular in axial plan view, and a corresponding outer edge, wherein the bearing plate (42) has, in the end face facing away from the stator housing (52), two grooves running around the passage of the shaft (66), wherein an annular circumferential lip (39) is formed on the fan wheel (36) around the fastening area (37) provided for attachment to the shaft (66), and the lip (39) is directed towards the bearing plate (42) and protrudes to form a non-contact seal, wherein the lip (39) projects into one of the grooves of the bearing plate (42), an air gap being provided between the lip (39) and the groove, wherein the groove is deeper than an axial distance between a bearing shield-side end face of the floating bearing (44) and a support surface of the spring element on the bearing shield (42), wherein the remaining opening of the passage of the bearing plate (42) is sealed by a shaft seal (30), wherein an axial receiving area of ​​the shaft sealing ring (30) in the bearing plate (42) is longer in the axial direction than a depth of the grooves in the bearing plate (42), wherein a fan cover (35) is placed at least partially overlapping onto the bearing plate (42), wherein the fan cover (35) has the shape of an approximately square shell with rounded corners and a flat bottom, wherein L-shaped recesses are arranged in wall sections of the rounded corners on the stator housing side, which are surrounded by further C-shaped recesses. [2] Electric motor according to claim 1, characterized bythat a pressing force generated by the spring element (41) is smaller than a maximum axial force that can be absorbed by the bearing. [3] Electric motor according to claim 2 or 1, characterized by , that the housing comprises a bearing plate (42) and the bearing plate (42) has a shaft passage which runs through a thickened area of ​​the bearing plate. [4] Electric motor according to claim 3, characterized by that the thickened area is shaped towards the inside of the housing. [5] Electric motor according to claim 3 or 4, characterized by that the bearing plate (42) has struts extending radially from the thickened area to a circumference of the bearing plate (42) for stiffening on the side facing into the housing. [6] Electric motor according to one of claims 3 to 5, characterized bythat a hollow cylinder which is completely open to the interior of the housing and has a larger diameter than the shaft passage is arranged centered around the shaft passage in the thickened area and this hollow cylinder is designed as a bearing holder for the loose bearing (44). [7] Electric motor according to one of the preceding claims characterized by that the housing comprises a flange plate (68) and a stator housing (52), and cooling fins (54) project approximately radially from the stator housing (52) parallel to one another. [8] Electric motor according to claim 7, characterized by that the free ends of the cooling fins (54) lie in a flat support surface, in particular in four flat support surfaces arranged approximately at right angles to one another. [9] Electric motor according to one of the preceding claims characterized by that the housing has a junction box. [10] Electric motor according to claim 9, characterized bythat the terminal box has a terminal box base (112) and a terminal box cover (132), a seal for the terminal box cover (131) which is clamped between the terminal box cover (132) and the terminal box base (112) and a seal for the terminal box base (111) which is clamped between the terminal box base (112) and a terminal box base (56) formed on the housing. [11] Electric motor according to one of claims 9 or 10, characterized by that a terminal plate (115) is fastened in the terminal box base (56), the terminal plate (115) has at least one threaded rod with a screw nut and a washer that can be screwed onto the threaded rod. [12] Electric motor according to one of claims 9 to 11, characterized by that various clamping devices are arranged in the terminal box base (112). [13] Electric motor according to one of claims 9 to 12, characterized by that cable ducts are arranged in one wall of the terminal box base, which can be closed by means of locking screws with O-rings (129,134) of a suitable size. [14] Electric motor according to claim 13, characterized by that the floor is formed by a grid structure. [15] Electric motor according to one of claims 12 to 14, characterized by that a circumferential wall of the fan cover (35) has a first partial section formed parallel to the axial direction of the shaft (66) and a second partial section running inwards in a funnel shape at an angle to the axial direction of the shaft (66). [16] Electric motor according to claim 15, characterized by that the first section towards the housing has a corresponding circumference suitable for partially overlapping fitting onto the bearing plate (42), which circumference decreases by a step towards the bottom of the fan cover (35). [17] Electric motor according to one of the preceding claims, characterized by that a fan wheel (36) is connected to the shaft (66) in a rotationally fixed manner, in particular is connected to the shaft (66) in a form-fitting manner. [18] Electric motor according to claim 17, characterized by that the fan wheel (36) is arranged axially outside the housing following the bearing plate (42). [19] Electric motor according to one of claims 17 or 18, characterized by that the fan wheel (36) has a radially projecting fan disc forming a truncated cone shell with its base surface open towards the bearing plate (42). [20] Electric motor according to claim 19, characterized by that the fan disc merges radially towards the shaft (66) into a fastening area (37) of the fan wheel (36) which is U-shaped in section and an innermost edge of the fastening area (37) forms the inner jacket of a fan wheel cylinder which is in contact with the shaft (66). [21] Electric motor according to claim 20, characterized bythat the shaft-side leg of the U of the fastening area is fixed by a further shaft diameter step of the shaft (66) and a retaining ring (32). [22] Electric motor according to one of claims 19 to 21, characterized by that the fan wheel (36) has at least one fan blade (38) which is approximately perpendicular to the fan disc. [23] Electric motor according to one of claims 1 to 22, characterized by that the groove is deeper than a length change range that can be compensated by the axially movable arrangement of the floating bearing (41), in particular in the operating temperature range. [24] Electric motor according to one of the preceding claims, characterized by that the fan wheel (36) is formed in one piece from plastic or aluminum.

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