Electric motor

Abstract

The utility model relates to an electric motor. The electric motor comprises a stator (1); a rotor (2) surrounding the stator (1); a shaft (3) which is non-rotatably connected to the rotor (2); and a housing surrounding the rotor (2) and the stator (1), in which the shaft (3) has a first end arranged in the housing and a second end protruding from the housing, and the rotor (2) comprises a back iron ring (9) and a permanent magnet (10) attached to an inner side of the back iron ring (9). According to the motor, the rotor (2) is provided with a support (11), the back iron ring (9) is connected to the shaft (3) through the support, the shaft (3) penetrates through the support in a protruding mode, the support (11) is attached to the shaft (3) between the second end portion of the shaft (3) and a bearing, and the bearing comprises a floating bearing (13) and a fixed bearing (12).

Description

Technical Field

[0001] The present utility model relates to an electric motor, which includes: a stator; a rotor surrounding the stator; a shaft connected to the rotor; and a housing, a first end of the shaft being disposed in the housing and a second end of the shaft protruding from the housing. For example, an electric motor having the above characteristics is known from EP 3 091 637 B1. Background Art

[0002] Compared with an inner rotor motor, an outer rotor motor with permanent magnets has mechanical advantages, especially when the permanent magnets are pressed against the rotor by centrifugal force during operation, and thus their installation can be designed to be simpler.

[0003] In many applications (such as in vehicles), it is necessary to protect the electric motor from environmental influences. In such applications, it is advantageous that the first end of the shaft in the outer rotor motor is disposed in the housing, because the housing then contains fewer points affected by the environment, especially moisture, which may penetrate and damage the electric motor.

[0004] In the electric motor known from EP 3 091 637 B1, the shaft is mounted in an opening of the housing. Therefore, the shaft can only be supported by bearings over a relatively short length and may thus be inclined relatively easily. Summary of the Utility Model

[0005] The object of the present utility model is to show an improved way of bearing the shaft of an electric motor of the above type.

[0006] This task is solved by an electric motor, which includes: a stator; a rotor surrounding the stator; a shaft non-rotatably connected to the rotor; and a housing surrounding the rotor and the stator, wherein the shaft has a first end disposed in the housing and a second end protruding from the housing, and the rotor includes a back iron ring and permanent magnets attached to the inner side of the back iron ring, the rotor has a bracket, the back iron ring is connected to the shaft via the bracket and the shaft protrudes through the bracket, and the bracket is attached to the shaft between the second end of the shaft and a bearing, and the bearing includes a floating bearing and a fixed bearing.

[0007] In the electric motor according to the present utility model, the rotor includes a bracket, the back iron ring is connected to the shaft via the bracket and the shaft protrudes through the bracket. The bracket is attached to the shaft between the first end of the shaft protruding from the housing and the floating bearing and the fixed bearing. Therefore, the bracket enables the shaft to be mounted at two points at a relatively large distance apart, making it difficult for the shaft to tilt.

[0008] A floating bearing that can move axially relative to the shaft can compensate for manufacturing tolerances, while a fixed bearing can absorb axial forces and thus ensure a stable position of the shaft relative to the stator.

[0009] An advantageous improvement of the present utility model is that the fixed bearing is pressed against the stop by a clamping section. The clamping section can be fixed by means of a screw protruding through the clamping section. The clamping section can be a separate component or can extend from a ring surrounding the shaft as a radial protrusion. Regardless of how the clamping section is designed, the shaft can have a flange through which the shaft is connected to the support, whereby the flange protrudes radially outward further than the outer ring of the fixed bearing, and the flange has a recess through which the screw can be accessed during assembly. In this way, although the shaft has a flange that protrudes outward further than the outer ring of the fixed bearing and can only be accessed from one direction on the fixed bearing for assembly, the fixed bearing can also be axially fixed during assembly. Therefore, the flange is located in the housing, between the housing opening and the fixed bearing.

[0010] The fixed bearing is preferably located between the flange and the floating bearing. In this way, the shaft can be made robust when transmitting torque from the rotor and very little material of the shaft extends into the housing, thus allowing a greater distance between the two bearings.

[0011] A further advantageous improvement of the present utility model provides that the floating bearing is arranged at the first end of the shaft and the floating bearing abuts against an annular shoulder of the shaft on the side facing the fixed bearing, and the fixed bearing abuts against another annular shoulder of the shaft on the side facing the second end of the shaft. Therefore, the diameter of the shaft increases in at least two stages from the first end portion of the shaft. Preferably, the shaft has a section where the diameter increases between the two bearings, such as a conical section.

[0012] In addition, it is preferably provided that there is a clamping section which, together with a screw protruding through the clamping section, presses the fixed bearing against the stop, the shaft has a flange through which the shaft is connected to the support, the flange protrudes radially outward further than the outer ring of the fixed bearing, and the flange has a recess through which the screw can be operated during assembly.

[0013] In addition, it is preferably provided that the clamping section is designed as a radial protrusion extending from a ring surrounding the shaft.

[0014] In addition, it is preferably provided that the flange has a plurality of radially outward protruding protrusions and the recess is located between the plurality of radially outward protruding protrusions.

[0015] In addition, it is preferably provided that the flange is screwed to the support.

[0016] Furthermore, it is preferably provided that the clamping section is located in a radially extending groove of the housing part of the housing.

[0017] Furthermore, it is preferably provided that the housing has a first housing part forming a closed base and a second housing part, the shaft protruding from the second housing part, the first housing part having an inner part that extends into the stator and encloses a fixed bearing and a floating bearing in the stator.

[0018] Furthermore, it is preferably provided that the ring is screwed onto the first housing part.

[0019] Furthermore, it is preferably provided that the first housing part forms the stop, against which the fixed bearing bears.

[0020] Furthermore, it is preferably provided that the shaft thickens between the floating bearing and the fixed bearing. Description of the Drawings

[0021] Further details and advantages of the present invention are explained with reference to the accompanying drawings and to embodiments of the present invention.

[0022] Figure 1 A cross-sectional view of an electric motor is shown;

[0023] Figure 2 A detailed view of the electric motor in the axial viewing direction is shown, in which the housing part is removed and there is no bracket;

[0024] Figure 3 Shows Figure 2 in perspective view; and

[0025] Figure 4 Shows according to Figure 2 a detailed view without the shaft. Detailed Description of the Invention

[0026] Figure 1 The electric motor shown in includes: a stator 1; a rotor 2 surrounding the stator 1; and a shaft 3 that is non-rotatably (i.e., rigidly) connected to the rotor 2. The stator 1 and the rotor 2 are surrounded by a sealed housing having: a first housing part 4 that forms a closed base on which the stator 1 rests; and a second housing part 5 as a cover, from which the shaft 3 protrudes. The first end of the shaft 3 is thus arranged in the housing, and the second end of the shaft 3 is arranged outside the housing. The shaft 3 is mounted in a fixed bearing 12 and a floating bearing 13. The bearings can be designed as roller bearings, for example ball bearings.

[0027] The stator 1 includes a stack 6 of laminated sheets and a stator winding 8. The rotor 2 includes: a back iron ring 9 to which permanent magnets 10 are attached on the inner side thereof; and a bracket 11 via which the back iron ring 9 is connected to the shaft 3 and the shaft 3 projects through the bracket. The bracket 11 is attached to a flange 24 of the shaft 3 between the end of the shaft 3 protruding from the housing and the bearings 12, 13. In other words, the flange 24 is arranged between the second end of the shaft 3 located outside the housing and the two bearings 12, 13.

[0028] The first housing part 5 has an inner part 5a that extends into the stator 1 and circumferentially surrounds the two bearings 12, 13. The inner part 5a can be hollow and contain a cooling water channel 14. For example, an insert 15 can be arranged in the hollow inner part 5a of the housing part 5, and the insert together with the inner part 5a of the housing part 5 defines the channel 14. The insert 15 is covered by a cooling plate 31 that is attached to the first housing part 5, for example, by welding, and thus fixes the insert 15 relative to the housing part 5. On its side facing away from the shaft 3, the first housing part 5 can carry control electronics with a printed circuit board 16 for supplying power to the stator winding 8, and the printed circuit board is covered by a cover 18 attached to the first housing part 5, which cover is in the form of a plate, for example.

[0029] In the illustrated embodiment, another cooling channel section is formed between the cooling plate 31 and the insert 15, which contributes to the cooling of the control electronics. The high-power components of the control electronics can be arranged on the side of the printed circuit board facing the cooling plate 31 and in particular against the cooling plate 31. For example, the cooling plate 31 can have protrusions (such as ribs or pins) on its side facing away from the control electronics, which protrusions extend into the other cooling channel section and improve the thermal coupling of the cooling plate 31 with the cooling liquid in the other cooling channel section.

[0030] In the illustrated embodiment, the fixed bearing 12 is arranged between the floating bearing 13 and the flange 24 of the shaft 3, and the bracket 11 is attached to the shaft 3 via this flange. The floating bearing 13 is arranged at the first end of the shaft 3, i.e., at the end located in the housing. As Figure 1 shown, the shaft 3 forms a stop for the inner ring of the floating bearing 13, for example, in the form of an annular shoulder. The floating bearing 13 can be pressed against this stop by a snap ring supported on the housing part 5.

[0031] The fixed bearing 12 is pressed against the stop 23 by clamping sections 20 (for example, three or more clamping sections 20), and the screw 22 projects through these clamping sections. The stop 23 is immovable relative to the stator 1 and is formed, for example, by the first housing part 5, in particular by the inner part 5a of the first housing part. The clamping sections 20 can be designed as separate components or as radially outwardly projecting protrusions extending from a ring surrounding the shaft 3. Such a ring can be integrated into the outer ring of the fixed bearing 12 or designed as a separate ring abutting against the fixed bearing 12.

[0032] In particular, as Figure 3 shown, each of the clamping sections 20 is located in a groove which, in the illustrated embodiment, is formed in the inner part 5a of the housing part 5. Thus, the flange 24 of the shaft 3 can rotate on the clamping sections 20 and on the screw 22 that fixes the clamping sections 20.

[0033] As already mentioned, the shaft 3 has a flange 24 via which the shaft is connected to the support 11, for example by means of screws 26. Obviously, the flange 24 projects radially outward further than the outer ring of the fixed bearing 12 and the clamping sections 20, against which stop 23 the fixed bearing 12 is pressed by the clamping sections. As Figure 2 and Figure 3 shown, the flange 24 has recesses through which the screw 22 can be operated during assembly, and the clamping sections 20 are fixed by the screws so as to press the fixed bearing 12 against the stop 23. These recesses for accessing the screw 22 during assembly are formed as free spaces between the radially outwardly projecting protrusions 25 of the flange 24. The flange 24 can be screwed to the support 11 via these protrusions 25.

[0034] As Figure 1 shown, the shaft 3 is thickened between the floating bearing 13 and the fixed bearing 12. The diameter of the shaft 3 increases in several stages from its first end located in the housing to the flange 24. The first increase in diameter is caused by the shaft 3 forming a stop for the floating bearing 13. A further gradual increase in the diameter of the shaft 3 occurs at the fixed bearing where the shaft also forms a stop for the fixed bearing. The diameter of the shaft 3 can also increase between the floating bearing 13 and the locating bearing 12 (for example, in a conical section).

[0035] The two housing parts 4, 5 can be screwed together and a seal 28 can be pressed in between them. The shaft 3 is held in a bushing 30 in an opening of the housing through which the shaft projects and which is sealed with a shaft seal 29.

[0036] List of reference numerals

[0037] 1 Stator;

[0038] 2 Rotor;

[0039] 3 axes;

[0040] 4 housing parts;

[0041] 5 housing parts;

[0042] 5a inner part;

[0043] 6 sheet stack;

[0044] 8 stator windings;

[0045] 9 back iron ring;

[0046] 10 permanent magnet;

[0047] 11 bracket;

[0048] 12 fixed bearing;

[0049] 13 floating bearing;

[0050] 14 channel;

[0051] 15 insert;

[0052] 16 printed circuit board;

[0053] 18 cover;

[0054] 20 clamping section;

[0055] 22 screw;

[0056] 23 stop;

[0057] 24 flange;

[0058] 25 protrusion;

[0059] 26 screw;

[0060] 28 seal;

[0061] 29 shaft seal;

[0062] 30 bushing;

[0063] 31 cooling plate.

Claims

1. An electric motor, comprising: Stator (1), A rotor (2) surrounding the stator (1), a shaft (3) which is non-rotatably connected to the rotor (2), and a housing, the housing surrounding the rotor (2) and the stator (1), The shaft (3) has a first end arranged in the housing and a second end protruding from the housing, and The rotor (2) comprises a back iron ring (9) and a permanent magnet (10) attached to the inner side of the back iron ring (9). It is characterized in that The rotor (2) has a bracket (11), the back iron ring (9) is connected to the shaft (3) via the bracket and the shaft (3) protrudes through the bracket, and The bracket (11) is attached to the shaft (3) between the second end of the shaft (3) and a bearing, the bearing comprising a floating bearing (13) and a fixed bearing (12).

2. The electric motor according to claim 1, characterized in that a clamping section (20) which, together with a screw (22) protruding through the clamping section, presses the fixed bearing (12) against a stop (23), The shaft has a flange (24) via which the shaft is connected to the bracket (11), the flange (24) protruding radially outwards further than the outer ring of the fixed bearing (12), and The flange (24) has a recess through which the screw (22) can be accessed during assembly.

3. The electric motor according to claim 2, characterized in that The clamping section (20) is designed as a radial projection extending from a ring surrounding the shaft (3).

4. The electric motor according to claim 2, characterized in that The flange (24) has a plurality of protrusions (25) protruding radially outward, and the recess is located between the plurality of protrusions protruding radially outward.

5. The electric motor according to claim 2, characterized in that The flange (24) is screwed to the bracket (11).

6. The electric motor according to claim 2, characterized in that The clamping section (20) is located in a radially extending recess of a housing part of the housing.

7. The electric motor according to claim 1, characterized in that The floating bearing (13) is arranged at a first end of the shaft (3) and the floating bearing (13) abuts against an annular shoulder of the shaft (3) on its side facing the fixed bearing (12), and the fixed bearing (12) abuts against another annular shoulder of the shaft (3) on its side facing the second end of the shaft (3).

8. The electric motor according to claim 1, characterized in that The housing has a first housing part (5) forming a closed base and a second housing part (4) from which the shaft (3) protrudes, the first housing part (5) having an inner part (5a) which projects into the stator (1) and surrounds a fixed bearing (12) and a floating bearing (13) in the stator (1).

9. The electric motor according to claim 3, characterized in that The housing has a first housing part (5) forming a closed base and a second housing part (4) from which the shaft (3) protrudes, the first housing part (5) having an inner part (5a) which projects into the stator (1) and surrounds a fixed bearing (12) and a floating bearing (13) in the stator (1), the ring being screwed onto the first housing part (5).

10. The electric motor according to claim 8, characterized in that The electric motor has a clamping section (20) which, together with a screw (22) protruding through the clamping section, presses the fixed bearing (12) against a stop (23), the first housing part (5) forming the stop (23) against which the fixed bearing (12) is pressed.

11. The electric motor according to claim 1, characterized in that The shaft (3) is thickened between the floating bearing (13) and the fixed bearing (12).

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