Electric motor with fan

Abstract

Electric motor (50) with fan, wherein the fan includes a fan hood (35), wherein the fan hood (35) comprises a first axial fan hood section with a circumferential surface that is continuously curved and a second axial fan hood section with a further circumferential surface that has at least one circumferentially uncurved subsection, wherein the fan hood (35) has a recess, in particular a recess designed as a longitudinal slot open towards the electric motor (50), in which a grommet is clamped, wherein the fan hood (35) surrounds a brake and / or an encoder of the electric motor (50) designed as an angle measuring system, wherein the fan hood (35) has a recess in the circumferential surface and / or the further circumferential surface, wherein the first axial fan hood section surrounds a fan wheel (36) with a drive and the second axial fan hood section is at least partially overlapping and placed over a housing of the electric motor (50), wherein the first axial fan hood section has a circular cross-section and the second axial fan hood section has a rectangular cross-section with rounded corners, wherein the fan hood (35) has a transition section between the first axial fan hood section and the second axial fan hood section, wherein the transition section has a subsection forming a truncated cone shell surface and a forming subsection, where the forming section transforms the circular cross-section into the rectangular cross-section.

Description

[0001] The invention relates to an electric motor with a fan.

[0002] An electric motor with a fan is known from DE 10 2005 016 905 B3.

[0003] A fan cover for an externally ventilated electric motor is known from DE 198 03 441 C1.

[0004] A direct drive with rotary encoder is known from DE 10 2004 034 636 A1.

[0005] An electrical machine is known from DE 295 02 565 U1.

[0006] From DE 92 11 441 U1 a fan hood for the air guidance of externally ventilated electric motors is known.

[0007] From DE 10 2006 007 434 A1 an electric machine with liquid metal bearing is known.

[0008] One engine series is known from the DE 102 38 336 A1.

[0009] An electric motor is known from DE 103 53 330 A1.

[0010] From DE 10 2005 016 905 B3 an electric motor with fan and associated fan cover is known.

[0011] The invention is therefore based on the objective of further developing an electric motor with a fan in a cost-effective and robust manner.

[0012] According to the invention, the problem is solved in the electric motor according to the features specified in claim 1.

[0013] Important features of the invention in the electric motor are that the electric motor comprises a housing, a stator, a rotor and a fan, wherein the rotor comprises a rotor assembly and a shaft which has sections of different diameters separated by shaft diameter steps, wherein a fixed bearing in a flange shield of the housing and a floating bearing in a bearing shield of the housing support the shaft, wherein the stator is mounted in a stator housing of the housing, wherein the fan comprises a fan hood, wherein the fan hood comprises a first axial fan hood section with a circumferential surface which is continuously curved and a second axial fan hood section with a further circumferential surface which has at least one section which is not curved in the circumferential direction.The first fan housing section surrounds a fan wheel with a drive, and the further fan housing section is at least partially overlapping and fits over a housing of the electric motor. A fan connection box is attached to the fan housing, wherein an end face, a mounting for a fan motor, and a fan connection box base are formed in one piece and attached to the fan housing. An advantage of this design is that a square housing for the electric motor with a round fan is possible under ideal airflow conditions, thereby suppressing vibrations.

[0014] Key features of the invention for the electric motor are that the fan comprises a fan housing, the fan housing comprising a first axial fan housing section with a circumferential surface that is continuously curved, and a second axial fan housing section with a further circumferential surface that has at least one circumferentially uncurved subsection. An advantage of this is that a rectangular housing for the electric motor with a round fan is possible under ideal airflow conditions, thereby achieving stiffening against vibrations.

[0015] In an advantageous embodiment, the first axial fan shroud section surrounds a fan wheel with a drive, and the second fan shroud section is at least partially overlapped and placed over a housing of the electric motor. An advantage of this design is that the fan shroud is vibration-damping.

[0016] In a further advantageous embodiment, the first axial fan shroud section has a circular cross-section, and the second axial fan shroud section has a rectangular cross-section with rounded corners. The advantage of this is that the fan shroud fits snugly around the electric motor housing and surrounds the fan wheel. Furthermore, the number of possible natural vibration modes is reduced.

[0017] In a further advantageous embodiment, the fan housing has a transition section between the first axial fan housing section and the second axial fan housing section. This transition section comprises a subsection forming a truncated conical surface and a formed subsection. An advantage of this design is that the fan housing is constructed in one piece and is particularly stable. Since the different fan housing sections have different natural frequencies, sound radiation and noise generation at the fan housing are also reduced.

[0018] In a further advantageous embodiment, the forming section transitions from a circular cross-section to a rectangular cross-section. The advantage here is that the fan hood can be manufactured in one piece with smooth surfaces free of edges and indentations, thus preventing the accumulation of dirt.

[0019] In a further advantageous embodiment, a fan connection box is attached to the fan housing. The advantage here is that the fan operates independently of the motor. Furthermore, the fan is additionally stiffened, thus reducing vibrations.

[0020] In a further advantageous embodiment, the fan has an end face facing away from the electric motor with an opening. The advantage here is that air not heated by the electric motor is drawn in by the fan. The end face also stiffens the fan housing.

[0021] In a further advantageous embodiment, the front surface, a mounting for a fan motor, and a fan connection box base are formed in one piece and attached to the fan housing. The advantage of this design is that the airflow is efficient and the fan can be manufactured simply and cost-effectively with few individual parts.

[0022] In a further advantageous embodiment, the fan is an axial fan that can be controlled independently of the electric motor. The advantage here is that the fan can always be operated in one direction of rotation, independent of the direction of rotation of the electric motor, and, compared to a radial fan with air deflection, moves a large amount of air past the electric motor for cooling.

[0023] In a further advantageous embodiment, the fan housing has a recess, in particular a longitudinal slot open towards the electric motor, into which a grommet is clamped. The advantage of this is that various connecting cables for components, which are routed from the fan housing through the grommet, can be safely guided under the fan housing. The grommet also stiffens the fan housing and reduces vibrations. The recess reduces the number of natural vibrations of the fan housing.

[0024] In a further advantageous embodiment, the fan housing surrounds a brake and / or an encoder for the electric motor, designed as an angle measuring system. The advantage here is that the electric motor can be manufactured cost-effectively and easily.

[0025] In a further advantageous embodiment, the fan housing has a recess in its circumferential surface and / or its outer circumferential surface. The advantage here is that components of the electric motor surrounding the fan housing can be accessed without having to disassemble the entire fan.

[0026] Further advantages arise from the dependent claims. The invention is not limited to the combination of features of the claims. For those skilled in the art, further meaningful combinations of claims and / or individual claim features and / or features of the description and / or the figures will become apparent, in particular from the problem statement and / or the problem arising from a comparison with the prior art. The invention will now be explained in more detail with the help of illustrations:

[0027] They show, purely schematically: - Fig. 1 an electric motor according to the invention in a perspective front view, - Fig. 2 the in Fig. 1 shown electric motor according to the invention in a perspective rear view and - Fig. 3 den in Fig. 1 shown in a longitudinal section of the electric motor according to the invention.

[0028] The electric motor 50 has an approximately cylindrical stator housing 52 with cooling fins 54 arranged parallel to each other and projecting approximately radially from the stator housing. The free ends of the cooling fins 54 rest in a flat contact surface, in particular in four flat contact surfaces arranged approximately at right angles to each other. Trapezoidal ridges 55 at the end faces of the outer surfaces of the stator housing 52 form corner elements between the flat contact surfaces. In at least one of the flat contact surfaces, four almond-shaped thickenings 58 of the cooling fins 54 have blind-hole mounting holes 60 with internal threads. These serve as mounting points for various attachments, such as a base plate, which in turn serves to mount the electric motor 50 in different positions.

[0029] A cuboid terminal box 110 is screwed onto a terminal box base 67 provided for this purpose. The terminal box base 67 is formed integrally with the stator housing 52 and projects 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 by means of a hexagon screw 123.

[0030] The end faces of the stator housing 52 are closed by further housing parts, such as a bearing shield 42 and a flange shield 64 – except for a passage for a shaft 66 in the flange shield 64 and a shaft passage in the bearing shield 42. A flange 7 for attaching driven devices is integrally formed on the flange shield 64. For this purpose, the flange 7 has a flange bore 8.

[0031] A socket head cap screw 13 is guided through bores in the bearing shield 42 and bores in the trapezoidal ridge on the stator housing 52 and screwed into an internal thread of a bore in a trapezoidal ridge on the flange shield 64. In this way, the flange shield 64 and the bearing shield 42 are pressed against the end faces of the stator housing 52 in a rotationally fixed manner. The housing of the electric motor 50 comprises the flange shield 64, the bearing shield 42, and the stator housing 52.

[0032] A fan hood 35 is attached to the circumference of the bearing shield 42, or partially overlapped with the bearing shield 42 in the axial direction and fastened to the bearing shield 42 with further hexagon screws 22.

[0033] The rotor 1 has a shaft 66 and a rotor assembly 72, which is fixed to the shaft 66 in a rotationally fixed manner, in particular by frictional locking. The shaft 66 has several shaft sections with different diameters in the axial direction. Due to the different diameters, the transitions between the shaft sections form several shaft diameter steps. The rotor assembly 72 is arranged approximately centrally on the shaft 66 in the shaft section with the largest shaft diameter and is fixed to this shaft section in a rotationally fixed manner, in particular by being pressed onto this shaft section.

[0034] 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 fixed on the shaft side by a retaining ring 10 and a shaft diameter step. The fixed bearing 11 is fixed on the stator housing side by the flange shield 64 and a retaining ring 12 for bores.

[0035] On the end shield side, a floating bearing 44, designed as a deep groove ball bearing, is mounted on the shaft 66 up to a further shaft diameter step. A compensating washer 41 is designed as an annular spring element and, viewed from the axial direction, has an approximately cloverleaf-shaped inner edge and a corresponding outer edge. "Cloverleaf-shaped" here refers to the outline of a four-leaf clover without a stem, or in other words, a circle that is symmetrically indented inwards at four points. To generate the spring effect, the compensating washer 41 is, for example, corrugated in the direction of rotation. The floating bearing 44 is movably fixed in a bearing receptacle in the end shield 42 between the further shaft diameter step and the compensating washer 41.Movable in the sense that the floating bearing 44 can follow axial displacements of the subsequent shaft diameter step due to a change in the length of the shaft 66, since the compensating washer 41 springs accordingly without deforming the floating bearing 44 or adversely altering 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 housing are accommodated.

[0036] A bearing shield end section of the shaft 66 protrudes from the bearing shield 42.

[0037] An interior of the housing is protected from contaminants such as dust, water, and / or gear oil by a splash guard 107 and a shaft seal 106 in the opening for the shaft 66 in the flange shield 64. A driven device can be flanged to the flange 7, particularly using stud bolts and hexagon nuts. A rotating part of this driven device can be fixed to the shaft 66 in a rotationally fixed manner, particularly by means of the key 3.

[0038] A sealing screw is used to close an oil inlet opening. If a gearbox is directly flanged to flange 7, gearbox oil can be supplied or exchanged via this oil inlet opening.

[0039] A stator 16 has a stator lamination stack 18 and a stator winding 20 with a winding head 21 and is mounted in the stator housing 52. The base plate is attached to the stator housing 52 with screws.

[0040] A terminal plate 115 is attached to the terminal box base 67 by means of a further screw 113. The terminal plate has at least one threaded rod designed as a connecting bolt with a nut and washer that can be screwed onto the threaded rod. In the stator housing 52, in the area of ​​the terminal box base 67, there are cable glands for intended connecting leads, such as connecting leads for the stator winding 20. The four inner corners of the terminal box base 67 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 lower part 112 and the terminal box base 67. The terminal box lower part 112 is screwed to the terminal box base 67 by means of fastening screws 119.Cable glands of various sizes are located in one wall of the terminal box base 112, which can be closed using appropriately sized sealing screws with O-rings. The end section 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 67. Various clamping devices are located on this ring, projecting into the interior of the terminal box base 112.

[0041] The terminal plate 115 and the various clamping devices are used for the electrical connection of externally supplied lines to the lines supplied from the electric motor 50 into the terminal box 110, such as the lines supplied from the stator winding 20. The clamping devices are designed, for example, as a connecting terminal 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 corresponding cuboid-shaped protrusion on the ring of the terminal box base 112. 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 hexagonal screws 123.

[0042] A nameplate 108 is attached to a flat mounting surface by means of a notched nail 109. The nameplate 108 bears the technically relevant parameters as well as the product designation for the electric motor 50.

[0043] A housing seal 392 is arranged between the bearing shield 42 and the stator housing 52. This seal is held in a rotationally fixed position by the socket head cap screws 13 via corresponding holes in the housing seal 392 and is clamped between the bearing shield 42 and the stator housing 52 in the assembled state. A shaft seal 30 closes the remaining opening of the passage in the bearing shield 42 when the shaft 66 is installed, in order to protect the interior of the stator housing 52 from contaminants such as dust and water.

[0044] For stiffening, the bearing shield 42 has radially outward-extending struts on the side facing the stator housing 52. The bearing shield 42 forms a thickening in the area of ​​the shaft passage. This thickening is shaped towards the stator housing 52. A hollow cylinder, completely open towards the stator housing, within the thickening of the bearing shield 42 is shaped concentrically with a larger diameter than the shaft passage and forms a cylindrical bearing receptacle for the floating bearing 44. Since the outer and inner rings of the fixed bearing are axially fixed, the floating bearing 44 does not have to absorb any axial forces acting on the shaft from the outside.

[0045] A thickened outer edge of the bearing shield 42 is also formed 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 shield 42 is a thickening which has a through-hole aligned parallel to the shaft 66 and a blind hole with an internal thread arranged perpendicular to it and extending radially to the shaft 66. The through-hole serves to receive the socket head cap screw 13 and the blind hole with internal thread for fastening the additional hexagon head screw 22.

[0046] The flange shield 64 and the bearing shield 42, together with the stator housing 52, enclose an approximately cylindrical interior space of the electric motor 50 and form the housing of the electric motor 50. The shaft 66 is supported relative to 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 shield 64 and is held on the shaft side by the shaft diameter step and the retaining ring 10. The retaining ring 10 snaps into an annular groove in the shaft 66. On the housing side, the fixed bearing 11 is held by an annular corner of the fixed bearing holder and by the retaining ring for a bore 12. The retaining ring for a bore 12 engages in a groove in the fixed bearing holder in the flange shield 64. The remaining opening of the shaft passage in the flange shield 64 is sealed by the shaft seal 106.

[0047] The stator 16, comprising the stator windings 20 with winding head 21 and the stator lamination stack 18, is fixed in the stator housing 52 by means of fasteners 80, in particular by being pressed into the stator housing 52. The rotor stack 72, pressed onto the shaft 66, has a rotor lamination stack 74. The laminations of the rotor lamination stack 74 are connected to one another, for example by stamping and / or by a rotor casting 76, which forms a squirrel cage for the rotor 1. The rotor casting 76, forming an annular ridge, projects axially from both sides of the rotor lamination stack 74 in the direction of the shaft 66.

[0048] The floating bearing 44 is arranged in the cylindrical bearing housing. The inner ring of the floating bearing 44, with its stator housing-side end face abutting a radial surface of a further shaft diameter step, provides shaft-side support to the rotor assembly 72. The compensating washer 41 is arranged between the floating bearing 44 and the bearing shield 42 in the cylindrical bearing housing and rests on a support surface in the bearing shield. The outer ring diameter of the compensating washer 41 is larger than the diameter of the shaft passage and less than or equal to the diameter of the cylindrical bearing housing. The inner opening diameter of the annular compensating washer 41 is at least as large as the shaft diameter of the shaft 66 in the region of the cylindrical bearing housing.Due to the special circumferentially corrugated shape of the annular compensating washer 41, the compensating washer 41 does not completely circumferentially contact the end face of an outer ring of the floating bearing 44 on the bearing shield side, but at least on one section. On the bearing shield side, the compensating washer 41 contacts the bearing shield 42 on at least another section of the support surface. This support surface only needs to absorb a spring force of the spring element in the axial direction. For example, in the special design as a cloverleaf-shaped compensating washer 41, the inwardly extended areas with the smaller outer diameter contact the flange shield, and the outwardly extended areas with the maximum outer diameter of the compensating washer 41 contact the outer ring of the floating bearing 41.When the shaft 66 undergoes an axial change 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 compensating washer 41.

[0049] 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 preload. In a further alternative embodiment, the spring element presses against both the inner and outer rings.

[0050] The shape and material of the compensating washer 41 are selected such that, during numerous length change cycles of the shaft 66 (i.e., expansion and contraction in the axial direction) over the service life of the electric motor 50, the floating bearing 44 is axially fixed by the compensating washer 41. The contact force of the compensating washer 41, taking into account manufacturing tolerances, is less than the maximum axial force that the floating bearing 44 can withstand. In particular, the contact force is adjustable by the number and / or shape of a rotating shaft of the annular compensating washer 41. Suitable materials for the spring element include metal, especially spring steel, which is also suitable for heat transfer between the bearing and the housing.

[0051] The bearing shield 42 has two grooves on its end face facing away from the stator housing 52, circumferentially encircling the shaft 66. The remaining opening of the bearing shield 42 is sealed by the shaft seal 30. An axial receiving area of ​​the shaft seal 30 in the bearing shield 42 is axially longer than the depth of the grooves in the bearing shield 42. The heat from the shaft seal 30 is dissipated past the grooves and further carried away radially outwards via the bearing shield 42 and the radially extending struts in the bearing shield 42.

[0052] Following the bearing shield 42 in the axial direction away from the housing is a fan 170. The fan 170 comprises a fan cover 35, a fan motor 34, a fan shaft 37, a fan wheel 36 with fan blades 38 and a fan connection box 39.

[0053] The fan shaft 37 is independent of the shaft 66 and is mounted in the fan and is rotationally fixed to the fan motor 34 or is formed in one piece with a fan motor shaft.

[0054] The fan shroud has a first axial section with a continuously curved circumferential surface. Extending axially from the housing, this is followed by a second axial section with another circumferential surface, including a section that is not curved in the circumferential direction. The first axial section has a circular cross-section. The second axial section has a rectangular cross-section with rounded corners. A transition section is arranged between the first and second axial sections. This transition section comprises a section forming a truncated conical surface and a forming section, and transforms the circular cross-section into the rectangular cross-section.

[0055] The first axial fan hood section has a corresponding circumference on the stator housing side, suitable for partially overlapping placement on the bearing shield 42.

[0056] The fan 170 has an end face facing away from the electric motor with an opening. This end face is integrally formed with a mounting for a fan motor 34 and a fan terminal box base. These are attached to the fan housing 35. The fan terminal box 39 is screwed onto the fan terminal box base. The fan terminal box contains various terminal connections and / or electronic components, such as rectifiers and / or capacitors, for externally supplied lines for controlling or supplying power to the fan. This allows the fan to be operated independently of the electric motor 50.

[0057] The first axial fan housing section surrounds a fan wheel 36 with a drive, and the second axial fan housing section is at least partially overlapped and placed over the bearing shield 42 of the electric motor. In the assembled state, the fan wheel 36 is positioned between the bearing shield 42 and the end face of the fan housing 35.

[0058] In the embodiment shown here, the fan is an axial fan.

[0059] In a further embodiment, the fan housing 35 has a recess, in particular a recess designed as a longitudinal slot open towards the electric motor 50, into which a grommet is clamped. The grommet is designed as a flexible, tubular cable gland, which preferably has an accordion-like shape.

[0060] In another embodiment, the fan housing surrounds a brake and / or an encoder of the electric motor designed as an angle measuring system. For maintenance of the brake or the encoder and for manual release of the brake, the fan housing 35 has recesses in its circumferential surface and / or the further circumferential surface, which can be closed by a cover corresponding to the shapes of the recesses.

[0061] Blind holes in the end faces of the shaft 66 and a snap ring 2 serve as further centering and / or fastening options for various driven elements. Reference symbol list 1 Rotor 2 snap rings 3 Key 4 more keyways 5 Flattening in the wave cross-section 7 flange 8 flange bore 10 retaining ring 11 fixed camps 12 retaining ring for bore 13 Cylinder screw 16 Stator 18 Stator lamination stack 20 Stator winding 21 winding head 22 more hexagon screws 30 shaft seals 32 additional retaining rings 34 Fan motor 35 Fan hood 36 fan wheel 37 Fan shaft 38 fan blades 39 Fan connection box 41 shim 42 Storage sign 44 Lotlager 50 electric motor 52 Stator housings 54 cooling fins 55 trapezoidal bulge 58 almond-shaped thickenings 60 mounting holes 64 Flange plate 66 wave 67 Junction box bases 72 Rotor package 74 Rotor lamination package 76 Rotor casting 80 Fasteners 106 Shaft seal 107 Splash guard 108 Type plate 109 notched nail 110 Junction box 111 Seal for the junction box base 112 Junction box base 113 more screws 115 terminal plate 116 clamping brackets 117 Clamping screw 118 Spring washer 119 Fastening screw 123 Hex bolt 131 Seal for the junction box cover 132 Junction box cover 170 external fans 392 Housing seal

Claims

[1] Electric motor (50) with fan, wherein the fan includes a fan hood (35), wherein the fan hood (35) comprises a first axial fan hood section with a circumferential surface that is continuously curved and a second axial fan hood section with a further circumferential surface that has at least one circumferentially uncurved subsection, wherein the fan hood (35) has a recess, in particular a recess designed as a longitudinal slot open towards the electric motor (50), in which a grommet is clamped, wherein the fan hood (35) surrounds a brake and / or an encoder of the electric motor (50) designed as an angle measuring system, wherein the fan hood (35) has a recess in the circumferential surface and / or the further circumferential surface, wherein the first axial fan hood section surrounds a fan wheel (36) with a drive and the second axial fan hood section is at least partially overlapping and placed over a housing of the electric motor (50), wherein the first axial fan hood section has a circular cross-section and the second axial fan hood section has a rectangular cross-section with rounded corners, wherein the fan hood (35) has a transition section between the first axial fan hood section and the second axial fan hood section, wherein the transition section has a subsection forming a truncated cone shell surface and a forming subsection, where the forming section transforms the circular cross-section into the rectangular cross-section. [2] Electric motor (50) according to claim 1, characterized by , that a fan connection box (39) is attached to the fan hood (35). [3] Electric motor (50) according to claim 1 or 2, characterized by , that the fan has an end face facing away from the electric motor (50) with an opening. [4] Electric motor (50) according to claim 3, characterized by , that the front surface, a mounting for a fan motor (34) and a fan connection box base (67) are formed in one piece and are attached to the fan hood (35). [5] Electric motor (50) according to claim 1, 2, 3 or 4, characterized by , that the fan is an axial fan which can be controlled independently of the electric motor (50). [6] Electric motor (50) according to claim 1, wherein the electric motor (50) comprises a housing, a stator (16), a rotor (1) and a fan, wherein the rotor (1) comprises a rotor assembly (72) and a shaft (66) which has sections with different diameters separated by shaft diameter steps, wherein a fixed bearing (11) in a flange plate (64) of the housing and a floating bearing (44) in a bearing plate (42) of the housing support the shaft (66), wherein the stator (16) is mounted in a stator housing (52) of the housing, wherein the fan includes a fan hood (35), wherein a fan connection box (39) is attached to the fan hood (35), wherein an end face, a receptacle for a fan motor (34) and a fan terminal box base (67) are formed in one piece and are attached to the fan hood (35).

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