Electric motor

Abstract

An electric motor comprising: a stator (1) comprising a stator winding (2); a rotor (3) surrounding the stator and comprising permanent magnets (4); a shaft (5) connected to the rotor; a housing surrounding the rotor and the stator; a cooling channel (6) is guided through an inner space surrounded by the stator, the shaft having a first end in the housing and a second end extending out of the housing, the housing comprising a first housing part (8) forming a base opposite the first axial end of the stator and a second housing part (9) as a cover, the second housing part being opposite the second axial end of the stator, the first housing part has an inlet (10) and an outlet (11) for a cooling liquid and an inner portion (8a) protruding into the stator. The stator has an inner portion forming a sleeve (8a ') in which the first end of the shaft is located, the inner portion further forming an annular space between the stator and the sleeve in which a cooling channel section for cooling the stator extends, at least one bearing (20, 21) of the shaft being located in the sleeve.

Description

Technical Field

[0001] The utility model relates to an external rotor motor with an internally cooled stator. Background Art

[0002] This type of electric motor is known, for example, from EP 3 091 637 B1.

[0003] An external rotor motor with an internally cooled stator (i.e., cooling channels extending through the interior surrounded by the stator) can achieve high performance in combination with a very compact design. A constant goal in the development of external rotor motors is to combine high performance with a compact design and high speed. Summary of the Utility Model

[0004] The object of the utility model is to show a way in which this goal can be better achieved.

[0005] This object is achieved by an electric motor having the features listed in the present invention. Advantageous improvements of the utility model are described below.

[0006] The electric motor according to the utility model comprises: a stator having a stator winding; a rotor having permanent magnets and surrounding the stator; a shaft coupled to the rotor; a housing surrounding the rotor and the stator; and cooling channels leading through the interior space surrounded by the stator. The housing has a first housing part and a second housing part, the first housing part forming a base opposite the first axial end of the stator, and the second housing part forming a cover opposite the second axial end of the stator. The first housing part has an inlet and an outlet for cooling liquid and an internal part extending into the stator. This internal part forms a sleeve and an annular space, one end of the shaft and a bearing of the shaft are arranged in the sleeve, the annular space is arranged between the stator and the sleeve, and a cooling channel section for stator cooling extends in the annular space.

[0007] In this way, the space surrounded by the stator can be used both for cooling the stator and for cooling the bearings of the shaft. Additionally, the support of the shaft can be improved by arranging a number of bearings at a greater distance than in the case of electric motors known from, for example, EP 3 091 637 B1.

[0008] An insert can be arranged in the annular space. Such an insert can then, together with the internal part, define the cooling channel section. However, this function of such an insert can also be taken over by the first housing part, i.e., the first housing part defines the cooling channel section without a separate additional component in its internal part.

[0009] The sleeve formed by the inner part can be provided integrally with the sleeve base, i.e., the first housing part forms both the sleeve and the sleeve base. In this case, the first housing part forms a pot-shaped member in which one end of the shaft is arranged. Another possibility is that the sleeve base is a separate component attached to the first housing part.

[0010] An advantageous refinement of the present invention provides that the shaft protrudes from the second housing part, i.e., the second housing part has an opening through which the shaft protrudes. This simplifies the structure of the two housing parts. However, the first housing part may also have an opening through which the shaft protrudes.

[0011] Another advantageous refinement of the present invention provides that the shaft has different diameters and is mounted in the sleeve via two bearings, wherein the first bearing is arranged closer to the end of the shaft located in the sleeve than the second bearing and has a smaller bearing inner diameter than the second bearing. In this way, the shaft and its bearing can be mounted in a simple manner by insertion into the sleeve formed by the first housing part. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Further details and advantages of the present invention are explained with reference to the accompanying drawings. In the various drawings, identical and corresponding parts are provided with corresponding reference numerals.

[0013] Figure 1 shows a cross-sectional view of an example of an electric motor according to the present invention;

[0014] Figure 2 The three sections defining the cooling passages of the electric motor are shown;

[0015] Figure 3 Shown Figure 1 a view of the rotor of the electric motor shown; and

[0016] Figure 4 A housing component of another embodiment of an electric motor according to the present invention is shown. DETAILED DESCRIPTION

[0017] Figure 1 The electric motor shown includes a stator 1 having a stator winding 2; a rotor 3 having permanent magnets 4 and surrounding the stator 1; a shaft 5 connected to the rotor 3 in a rotationally fixed manner; and a cooling channel section 6 extending through the interior space enclosed by the stator 1. The rotor 2 and the stator 1 are arranged in a housing comprising a first housing part 8 and a second housing part 9. A first end of the shaft 5 is arranged in the housing. A second end of the shaft 5 protrudes from the housing.

[0018] The first housing part 8 forms a base opposite the first axial end of the stator 1, while the second housing part 9 is a cover opposite the second axial end of the stator 1. In particular, the first housing part 8 also has Figure 2 shown in and has an inlet 10 and an outlet 11 for the cooling liquid.

[0019] The first housing part 8 has an inner part 8a that projects into the stator 1. This inner part 8a forms a sleeve 8a', in which the first end of the shaft 5 is arranged, and this inner part forms an annular space that is arranged between the stator 1 and the sleeve. The cooling channel section 6 extends in this annular space in order to cool the stator 1. Two bearings of the shaft 5, for example the second bearing 20 and the first bearing 21, are arranged in the sleeve 8a' formed by the inner part 8a. The cooling channel section 6 extending in the annular space thus cools the stator 1 on the one hand and the bearings on the other hand.

[0020] The shaft 5 has different diameters. The first bearing 21 (arranged closer to the end of the shaft 5 located in the housing than the second bearing 20) thus has a smaller bearing inner diameter than the second bearing 20. In the illustrated embodiment, the second bearing 20 is designed as a locating bearing. The second bearing 20 rests on the one hand on a stop formed by the housing part 8, more precisely on a stop formed by the inner housing part 8a, and on the other hand on a stop formed by the shaft 5. In the illustrated embodiment, the first bearing 21 is designed as a floating bearing that is elastically pressed against a stop formed by the shaft 5, for example by a spring washer 22. These different diameters thus allow for simple assembly, namely the second bearing 20 and the first bearing 21 are pushed onto the shaft 5 and then the shaft 5 is pushed into the inner housing part 8a.

[0021] An insert 12 is arranged in the annular space of the inner part 8a of the first housing part 8, and this insert together with the inner part 8a defines the cooling channel section 6 for cooling the stator 1. The insert 12 can have a circumferential rib 12a or a plurality of circumferential ribs 12a that extend in the circumferential direction, i.e., are oriented in the circumferential direction, and the cooling channel section 6 extends along these circumferential ribs. Alternatively or additionally, the insert 12 can also have one or more axial ribs 12b that extend in the axial direction in the annular space, i.e., are oriented in the axial direction, and the cooling channel section 6 extends along these axial ribs.

[0022] The first housing part 8 bears a plate 13 that encloses the insert 12 in the annular space. The plate 13 can be welded to the first housing part 8 or attached to the first housing part in some other way, for example by brazing or a threaded connection.

[0023] In Figure 1In the illustrated embodiment, the plate 13 defines another cooling channel section 14 between itself and the insert 12. This another cooling channel section 14 cools the electronic components 15 of the electronic control unit, such as transistor switches, which control the power supply to the stator winding 2. In the illustrated exemplary embodiment, this another cooling channel section 14 is arranged upstream of the cooling channel section 6 for cooling the stator 1, but it can also be arranged downstream thereof. The cooling channel section 6 for cooling the stator 1 is thus connected downstream of this another cooling channel section 14 for cooling the electronic components 15. In this way, particularly efficient cooling is achieved. The first housing part 8 carries the printed circuit board 16 on which the control electronics are arranged. The electronic components 16 are arranged on the side of the printed circuit board 16 facing the plate 13 and rest on the plate 13. The plate 13 is thus a cooling plate for one or more components of the control electronics.

[0024] The plate 13 can have protrusions 13a on its side facing away from the electronic components 15, which protrude into this another cooling channel section 14 and thus improve the heat dissipation from the plate 13. The printed circuit board 16 is covered by a cover (such as the cover plate 18) and is enclosed in the space defined by the first housing part 8 and the cover.

[0025] The printed circuit board 16 can be attached to the first housing part 8 using screws. Other mechanical fastening methods, such as adhesive bonding, can also be used. In particular, the first housing part 8 can have protrusions 8c on which the printed circuit board 16 is placed.

[0026] The inner part 8a of the first housing part 8 can have a cylindrical outer surface. However, for production as a casting, it may be advantageous if the outer surface of the inner part 8a is conical and defines a cone angle less than 20°, for example less than 10°.

[0027] The housing can be designed as a sealed housing, for example, a seal 23 is arranged between the first housing part 8 and the second housing part 9, for example, pressed between the first housing part 8 and the second housing part 9, and the shaft 5 is surrounded by a shaft seal 24 and guided out of the second housing part 9.

[0028] Figure 3The rotor 3 of the above-mentioned electric motor is shown. The rotor 3 has a backing iron ring 31 and a carrier 32. Permanent magnets 4 are attached to the inside of the backing iron ring. The carrier is attached to the backing iron ring 31 and has an opening 33 through which a shaft 5 projects. The opening 33 forms a hub for the shaft. In the illustrated exemplary embodiment, the shaft 5 is screwed to the carrier 32, particularly if the carrier 32 is made of an aluminum-based alloy. However, the carrier 32 can also be welded to the shaft, particularly if the carrier 32 is made of steel. The backing iron ring 31 can be formed as a stack of sheets, such as electrical steel or other soft magnetic steel. Each sheet of this stack of sheets can be annular; however, sheets that each form only a segment of the ring can also be used.

[0029] In Figure 1 the illustrated embodiment, the inner part 8a of the first housing part 8 includes a sleeve base 8b. The sleeve base 8b is thus integrally formed with the inner part 8a and the first housing part 8. However, the sleeve base 8b can also be a separate part attached to the first housing part 8. For example, a plate 13 can form the base of the sleeve 8a'.

[0030] Figure 2 Three components that together define the cooling channel sections 6, 14 are shown. These three components are the first housing part 8, the insert 12, and the plate 13. However, these three components 8, 12, 13 can also be formed as a single piece. Figure 4 A corresponding embodiment of the first housing part 8 is shown. As in Figure 1 and Figure 2 the embodiment, the first housing part 8 has an inner part 8a that extends into the stator 1 and forms a sleeve 8a' with a sleeve base 8b, and one end of the shaft 5 is arranged in the sleeve base. The inner part 8a of the first housing part 8 forms an annular space that is arranged between the stator 1 and the sleeve 8a', and the cooling channel section 6 extends in this annular space. The inner part 8a has at least one rib 19 that extends in the axial direction in the annular space, and the cooling channel section 6 extends along this rib for cooling the stator 1. Additionally, the inner part 8a also forms another cooling channel section 14 for cooling the electronic component 15 and has a plate 13 on which the electronic component 15 rests, as Figure 1 shown.

[0031] List of reference numerals

[0032] 1 Stator

[0033] 2 Stator winding

[0034] 3 Rotor

[0035] 4 Permanent magnet

[0036] 5 Shaft

[0037] 6 cooling channel sections

[0038] 8 first housing part

[0039] 8a inner part of the first housing part

[0040] 8a' sleeve

[0041] 8b sleeve bottom

[0042] 8c protrusion

[0043] 9 second housing part

[0044] 10 inlet

[0045] 11 outlet

[0046] 12 insert

[0047] 12a circumferential rib

[0048] 12b axial rib

[0049] 13 plate

[0050] 13a protrusion

[0051] 14 cooling channel sections

[0052] 15 electronic component

[0053] A printed circuit board

[0054] 18 cover plate

[0055] 19 rib

[0056] 20 second bearing

[0057] 21 first bearing

[0058] 22 spring washer

[0059] 23 seal

[0060] 24 shaft seal

[0061] 31 backing iron ring

[0062] 32 carrier

[0063] 33 opening

Claims

1. An electric motor comprising: A stator (1), comprising a stator winding (2), a rotor (3) surrounding the stator (1) and comprising permanent magnets (4), a shaft (5), the shaft being connected to the rotor (3), a housing enclosing the rotor (3) and the stator (1), and A cooling channel section (6) is provided, which leads through an interior space enclosed by the stator (1), wherein: - the shaft (5) has a first end arranged in the housing and a second end extending out of the housing, - the housing comprises a first housing part (8) forming a base opposite a first axial end of the stator (1) and a second housing part (9) serving as a cover, the first housing part forming a base opposite a first axial end of the stator (1), the second housing part opposite a second axial end of the stator (1), and - the first housing part (8) has an inlet (10) and an outlet (11) for the cooling liquid and an inner portion (8a) projecting into the stator (1), It is characterized in that The inner part (8a) forms a sleeve (8a') in which the first end of the shaft (5) is arranged, and the inner part (8a) also forms an annular space, which is arranged between the stator (1) and the sleeve (8a'), wherein a cooling channel section (6) for cooling the stator (1) extends in this annular space, And wherein at least one bearing of the shaft (5) is arranged in the sleeve (8a').

2. The electric motor according to claim 1, wherein An insert (12) is arranged in the annular space, which insert, together with the inner part (8a), defines the cooling channel section (6).

3. The electric motor according to claim 2, wherein: The first housing part (8) carries a plate (13) which encloses the insert (12) in the annular space.

4. The electric motor according to claim 3, wherein: The plate (13) forms the base of the sleeve (8a').

5. The electric motor according to claim 3 or 4, characterized in that The plate (13) defines a further cooling channel section (14) between itself and the insert (12), and the first housing part (8) carries a printed circuit board (16) with control electronics for controlling the power supply of the stator winding (2), the printed circuit board (16) carrying electronic components (15) on its side facing the plate (13), which bear against the plate (13).

6. The electric motor according to claim 5, characterized in that The plate (13) carries projections (13a) on its side facing away from the electronic component (15), which projections extend into the further cooling channel section (14).

7. The electric motor according to claim 5, wherein: The further cooling channel section is arranged upstream of the cooling channel section for cooling the stator (1).

8. The electric motor according to claim 1, wherein The inner portion (8a) has a cylindrical or conical outer surface defining a cone angle of less than 20°.

9. The electric motor according to claim 8, characterized in that The cylindrical or conical outer surface defines a cone angle of less than 10°.

10. The electric motor according to claim 1, wherein The shaft (5) has different diameters, the at least one bearing includes a first bearing (21) and a second bearing (20), and the shaft (5) is mounted in a sleeve (8a') formed by the inner portion (8a) through the first bearing (21) and the second bearing (20), the first bearing (21) being arranged closer to the first end of the shaft (5) than the second bearing (20) and having a smaller bearing inner diameter than the second bearing (20).

11. The electric motor according to claim 1, wherein A seal (23) is arranged between the first housing part (8) and the second housing part (9).

12. The electric motor according to claim 1, wherein The rotor (3) has a backing iron ring (31) and a carrier (32), the permanent magnet (4) is attached to the inside of the backing iron ring, and the backing iron ring (31) is connected to the shaft (5) via the carrier.

13. The electric motor according to claim 12, wherein: The carrier (32) has an opening (33) through which the shaft (5) projects.

14. The electric motor according to claim 1, wherein The shaft (5) protrudes from the second housing part (9).

15. The electric motor according to claim 2, wherein The insert (12) has at least one circumferential rib, which extends in the circumferential direction, and the cooling channel section (6) for cooling the stator (1) extends along the at least one circumferential rib of the insert (12).

16. The electric motor according to claim 1, wherein The first housing component (8) has at least one rib (19), the at least one rib of the first housing component (8) extending in the annular space in the axial direction, and the cooling channel section (6) for cooling the stator (1) extending along the at least one rib of the first housing component (8).

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