DE102012019415B4 - Electric motor, especially with a redundant brake arrangement - Google Patents

Abstract

Electric motor with a redundant brake arrangement, the electric motor having a bearing plate (1) which is connected to a housing part and/or the stator of the electric motor, the bearing plate (1) receiving a bearing (2) of the rotor shaft (3) of the electric motor, wherein a first and a second electromagnetically actuated brake are mounted on a bearing shield (1) of the electric motor, the first brake being arranged on a first side of the bearing shield (1) and the second brake being arranged on the other side of the bearing shield (1). , characterized in that the end shield (1) is pot-shaped, the pot bottom being arranged on the axial side of the pot facing away from the stator, with a recess on the pot bottom of the end shield in a thickening of the pot bottom that rises towards the stator, in which holds the bearing (2) of the rotor shaft (3). The friction disk (26) of the first brake is attached to the magnet body via a pressure sleeve (602), namely via a pressure sleeve (602) which acts as a guide pin (25), by means of a screw (43) is screwed onto the first brake, with the pressure sleeve (602) guiding the armature disk (24) in the axial direction, with the screw protruding through the pressure sleeve (602), with the pressure sleeve (602) between the friction disk (26) and the magnetic body ( 43) is arranged in between, the magnet body (43) having a bore into which a pressure sleeve (602) is at least partially inserted, the friction disk (26) being pressed towards the magnet body (43) by means of a screw over the pressure sleeve (602). ,wherein an O-ring (601) is fitted onto the pressure sleeve (602) and/or an O-ring (601) is arranged between the pressure sleeve (602) and the armature disk (13, 24).

Description

The invention relates to an electric motor, in particular with a redundant brake arrangement.

From this it is known in a brake motor to equip an electric motor with an electromagnetically actuated brake, in particular as a brake mounted on the B side.

From the DE 10 2010 049 748 A1 an electric motor with a first and second brake is known.

The invention is therefore based on the object of increasing safety in a system.

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

Important features of the invention in the electric motor, in particular with a redundant brake arrangement, are that the electric motor has a bearing plate which is connected to a housing part and/or the stator of the electric motor,
wherein the end shield accommodates a bearing of the rotor shaft of the electric motor,
wherein a first and a second electromagnetically actuated brake are mounted on a bearing plate of the electric motor,
wherein the first brake is arranged on a first side of the end shield,
arranged in particular on the axial side of the end shield facing the stator,
and the second brake is arranged on the other side of the end shield,
is arranged in particular on the axial side of the end shield facing away from the stator.

The advantage here is that a brake system that can be operated redundantly is provided and thus safety can be increased. The first brake is installed in the engine interior and the second brake is installed as an add-on brake. Both brakes are attached to the end shield of one of the rotor shaft bearings. This means that both brakes can be mounted on the end shield and then this end shield can be connected to the stator or the rest of the motor housing.

In an advantageous embodiment, each brake has an electromagnet and an axially movable armature disk which is arranged in a form-fitting manner with play or play-free in the circumferential direction, which is moved axially towards the respective electromagnet when the electromagnet is energized against the spring force of a respective spring element and which is moved when the electromagnet is not energized of the electromagnet is pressed by the respective spring element onto a brake pad carrier, which is thus pressed onto a braking surface, in particular a friction disk. The advantage here is that if the power supply fails, the brake is automatically applied because the armature slide is pressed against the lining carrier by at least one spring element, which is thus pressed onto the friction disk.

In an advantageous embodiment, the lining carrier of the first and/or the second brake is axially movable but non-rotatably connected to the rotor shaft of the electric motor or to a driver part which is non-rotatably connected to the rotor shaft,
in particular, the lining carrier has an internal toothing which engages with an external toothing of the rotor shaft or the driver part,
in particular, the driver part being connected to the rotor shaft by means of a feather key connection. The advantage here is that the lining carrier is arranged on the driver part in an axially displaceable manner and can therefore be pressed onto the friction disk by the armature disk. The teeth of the toothing therefore preferably only extend in the axial direction.

In an advantageous embodiment, the internal toothing and/or the external toothing is an involute toothing. The advantage here is that production is easy to carry out, as a widely used type of gearing can be selected.

In an advantageous embodiment, a spring element is arranged between the internal toothing and/or external toothing to reduce or suppress play. The advantage here is that the wear of the teeth can be reduced, especially when the motor is powered by a converter and the motor is operated frequently at a constant target speed, i.e. when speed fluctuations are exposed to long periods of time.

According to the invention, the end shield is pot-shaped, with the pot bottom being arranged on the axial side of the pot facing away from the stator. The advantage here is that a particularly compact structure can be achieved and the first brake can be completely or at least partially covered axially by the wall of the pot.

According to the invention, there is a recess on the pot bottom of the end shield in a thickening of the pot bottom that rises towards the stator, in which the bearing of the rotor shaft is accommodated. The advantage here is that a stable mounting of the bearing can be provided.

In an advantageous embodiment, an at least partially axially extending air gap is arranged between the end shield and the driver part of the first brake. The advantage here is that particles of brake abrasion cannot migrate out of the spatial area of the brake and a seal is therefore achieved.

In an advantageous embodiment, the end shield is held together with the housing part and/or stator of the electric motor by means of tie rods. The advantage here is that a simple, cost-effective connection of the housing parts can be achieved.

In an advantageous embodiment, the magnetic body of the first brake is screw-connected to the end shield,
in particular, the screws being screwed in from the side of the end shield facing away from the stator, in particular the cup bottom of the end shield. The advantage here is that the first brake and also the second brake can be attached to the end shield. The first brake is designed as a built-in brake and the second brake as an add-on brake.

According to the invention, the friction disk of the first brake is screwed to the magnetic body of the first brake by means of a screw via a pressure sleeve, in particular a pressure sleeve which acts as a guide pin,
whereby the pressure sleeve guides the anchor slide in the axial direction,
whereby the screw protrudes through the pressure sleeve,
in particular, the pressure sleeve being arranged between the friction disk and the magnetic body. The advantage here is that the friction disk can be easily attached to the magnetic body, with the pressure sleeve also taking on the function of axially guiding the armature disk.

In an advantageous embodiment, the housing part accommodates the stator windings and has a recess on its side facing the end shield, which is covered by a protective cap, in particular a plastic protective cap,
wherein the protective cap has a recess for the passage of the rotor shaft, the protective cap being designed to be axially widened towards its smallest radial distance in order to form a gap seal towards the rotor shaft,
in particular, the air gap between the rotor shaft and the protective cap is smaller than an average-sized abrasion particle falling off the friction lining during braking,
wherein the end shield touches the housing part radially outside the radial distance area covered by the protective cap and/or is connected to the housing part. The advantage here is that a cost-effective, simple seal can be achieved.

In an advantageous embodiment, the rotor shaft has a shoulder, in particular a circumferential edge, which is arranged axially next to the axial region covered by the protective cap,
in particular for throwing off abrasion particles before they enter the gap seal arranged between the rotor shaft and the protective cap. The advantage here is that particles are thrown off in the spatial area before entering the gap sealing area between the protective cap and rotor shaft, thus further improving the seal.

In an advantageous embodiment, a fan is arranged on the axial end region of the rotor shaft, the cooling air flow of which is directed along the second brake and along axially extending cooling fins, the cooling fins being arranged on the outside of the end shield, in particular being designed in one piece with the end shield. The advantage here is that heat dissipation of the brakes can be achieved in a simple manner. In particular, the end shield can be heat-cooled particularly effectively due to the integrally formed cooling fins. Since the brakes are mounted on the end shield, in particular screw-connected, effective heat dissipation of the brakes can be achieved.

In an advantageous embodiment, a guide pin guides the armature disk in the axial direction and is screwed with its threaded area arranged in an axial end region of the guide pin into a threaded hole in the magnet body of the first brake, in particular so that the guide pin rests with a collar on the flat surface of a threaded hole associated Lowering on the magnet body,
wherein the guide pin has a threaded hole into which a screw is screwed, which fixes the friction disk of the first brake on the guide pin,
wherein the guide pin has an external hexagon region or internal hexagon region, in particular at its axial end region facing the friction disk. The advantage here is that the friction disk can be easily attached to the magnet body, which also functions as an axial guide for the armature disk.

According to the invention, the magnetic body has a bore into which a pressure sleeve is at least partially inserted,
whereby the friction disk is pressed towards the magnet body via the pressure sleeve by means of a screw,
wherein the pressure sleeve is arranged between the friction disk and the magnetic body. It is advantageous to that a cost-effective, simple attachment of the friction disk to the magnet body can be carried out. In addition, the pressure sleeve is also used as an axial guide for the armature disk.

According to the invention, an O-ring is fitted onto the pressure sleeve and/or an O-ring is arranged between the pressure sleeve and the armature disk. The advantage here is that the shock load on the armature disk can be reduced.

Further advantages result from the subclaims.

The invention will now be explained in more detail using illustrations:

In the 1 a cross section through a brake motor according to the invention is shown.

In the not according to the invention 2 is essentially an enlarged section of the in 1 shown cross section, whereby instead of the screw 42 1 a screw 201 screwed into a guide bolt 202 is inserted and the guide bolt has a hexagon socket.

In the not according to the invention 3 is essentially a section of a too 2 shown in a top view.

In the not according to the invention 4 is essentially an enlarged section of the in 1 shown cross section, whereby instead of the screw 42 1 a screw 401 screwed into a guide bolt 402 is inserted and the guide bolt has an external hexagon.

In the not according to the invention 5 is essentially a section of a too 4 shown in a top view.

In the 6 is essentially an enlarged section of the in 1 shown cross section, whereby instead of the screw 42 1 a screw 603 is arranged in a pressure sleeve 602, which is sealed with an O-ring 601.

In the 7 is essentially a section of a too 6 shown in a top view.

In the 8th is essentially an enlarged section of the in 1 Cross section shown, a protective cap 28, in particular a plastic cap, for sealing the engine interior is shown in more detail.

In the 9 is essentially a to 8th assigned top view shown.

In the 10 is essentially an enlarged section for 8th shown, with the engagement of the protective cap 28 being shown in more detail.

As in 1 shown, the motor according to the invention is designed with a redundant brake system, so that increased safety can be achieved.

For this purpose, a first bearing 2 of the rotor shaft 3 is accommodated in a bearing shield 1. Another bearing of the rotor shaft 3 is arranged on the axial side of the motor facing away from the rotor 32 arranged on the rotor shaft 3.

The rotor 32 together with the rotor laminated core is thus arranged axially between the two bearings of the rotor shaft 3. The stator laminated core is also arranged between the bearings. The stator laminated core accommodates stator windings, the deflection areas of which, i.e. winding head 30, is arranged axially between the stator laminated core and the bearing 2.

The first brake is thus arranged on the axial side of the end shield 1 facing the stator. The second brake is arranged on the axial side of the end shield 1 facing away from the stator.

The end shield 1 is constructed like a pot, with the bearing 2 being accommodated on the bottom of the pot. The rotor shaft 3 is tapered through the bottom of the pot and protrudes through the second brake and accommodates a fan 17 at its axial end region. The fan promotes a fan flow in the axial direction, in particular by guiding the air flow through the fan cover 9, along the cooling fins 38, which are arranged on the radially outer circumference of the end shield 1 as viewed from the rotor shaft axis.

To form the first brake, a driver 4 is attached to the rotor shaft 3, in particular connected in a rotationally fixed manner. The driver 4 has driver teeth on its radially outer circumference as seen from the rotor shaft axis.

A brake disk 37, in particular a brake pad carrier, is arranged on the driver 4 and has internal teeth corresponding to the driver teeth.

The brake disc has brake linings on both of its axial end faces. Since the teeth of the toothing extend in the axial direction, i.e. parallel to the rotor shaft axis direction the brake disc is axially movable but positively connected in the circumferential direction to the driver 4 and thus also indirectly to the rotor shaft 3.

A magnetic body 43 is accommodated in a recess in the end shield 1 that is open towards the rotor 32. The magnet body is made of cast steel, in particular GGG cast, and is ferromagnetic. The brake coil 33, designed as a ring winding, is inserted into a coil carrier 31 made of plastic, which in turn is accommodated in a recess in the magnet body 43, which is also open towards the stator.

Between the brake disk 37 and the brake coil 33 there is an axially movable but non-rotatably connected armature disk 24 connected to the end shield 1 in the circumferential direction. When the brake coil 33 is energized, the armature disk is therefore attracted to the magnetic field emerging from the magnetic body 43.

Compression springs press against the magnetic force on the armature disk in the axial direction. When the brake coil 33 is not energized, the armature disk is therefore pushed away from the magnet body 43. Here, the brake disc 37 is pressed onto the friction disc 26, so that the brake pads of the brake disc 37 provided on both sides generate frictional force towards the armature disc 24 and the friction disc 26.

The friction disk 26 is screwed to the bearing plate 1 by means of the screw 42, with a guide bolt 25 being arranged in between, which guides the armature disk 24 during its axial movement, in particular preventing it from rotating.

The screw 42 is designed as a countersunk screw and presses the friction disk 26 with the screw head of the screw 42 onto the guide bolt 25.

A plurality of screws 42 and guide bolts 25 which have the same effect and are preferably evenly spaced apart from one another in the circumferential direction are arranged in the circumferential direction.

The coil carrier 31 is preferably cast with the brake coil 33 using casting compound and is therefore not only non-positively but also materially connected to the magnetic body 43.

The screw 42 is screwed with its threaded section into a threaded hole in the end shield 1. The magnet body 43 is screw-connected to the end shield 1 by means of the screw 41.

The second brake is provided on the side of the end shield 1 facing away from the first brake in the axial direction.

The second brake is also mounted on the end shield 1 like the first brake and, like the first brake, is designed as an electromagnetically actuated brake.

For this purpose, a stud screw part 19 is screwed into a threaded hole in a friction disk 22, which is fixed to the magnet body 8 by means of an adjusting nut 18, so that the magnet body 8 is limited to a maximum distance in the axial direction.

This maximum distance can be adjusted by screwing the adjusting nut 18, so that the air gap between the armature disk 13 of the brake and the brake coil can be adjusted when the brake pads are worn.

A pressure sleeve 16 and spring element 15 are arranged between the friction disk 22 and the magnetic body 8, the spring element 15 being supported on the friction disk 22 and pressing on the pressure sleeve 16, which in turn is supported on the magnet body 8.

In the circumferential direction, further pressure sleeves 16 with spring elements 15 are arranged around stud screw parts 19, in particular at regular intervals from one another in the circumferential direction, in particular arranged plugged onto them.

A sealing part 40 is provided at a greater radial distance than the pressure sleeves 16 and spring elements 15, which is thus arranged axially between the friction disk 22 and the magnetic body 8.

To form the second brake, a driver part 4 is again arranged on the rotor shaft 3 and is arranged in a rotationally fixed manner, preferably without play in the circumferential direction by means of a spring element 5, the driver part 4 having driver teeth 11, so that the lining carrier 12, designed as a double disk, is arranged to be axially movable, wherein brake pads 14 are arranged axially on both sides of the pad carrier 12. With a first brake pad 14, when the brake coil 6 is not energized, the armature disk 13 is pressed by compression springs supported on the magnetic body 8 and the pad carrier 12 is pressed against the friction disk 22 via its brake pad 14. When the brake coil 6 is energized, the armature disk 13 is attracted to the magnetic body 8 and the lining carrier 12 and the brake linings are released, i.e. the second brake is released.

On the magnetic body 8, in particular a ferromagnetic steel casting, a shaft sealing ring is arranged, in particular non-positively connected, the shaft sealing ring having two sealing lips which seal towards the rotor shaft. In this way, brake abrasion is prevented from getting from the area of the second brake into the spatial area of the fan 17 arranged at the axial end area of the rotor shaft 3 and thus into the environment.

The brake coil 6 of the second brake is again designed as a ring winding and is inserted into a coil carrier 7. The annular arrangement formed in this way is inserted into the magnetic body 8, similar to the first brake, so that the magnetic field emerging axially from the area wrapped around by the ring winding is guided through the magnetic body and is guided around the ring winding by approximately 180 °, so that the field is on Compared to the radial distance of the ring winding, a smaller radial distance is introduced into the magnet body in the axial direction and is guided out of the magnet body 8 at a larger radial distance in comparison to the radial distance of the ring winding, counter to the axial direction.

The fan cover is detachably connected to the end shield, in particular screw-connected.

The driving gears (11) of both brakes can be designed as non-helical spur gears, with involute profile sections preferably being used for the teeth of the gearing.

The stud screw part 19 is passed through the spring element 15 and also through the pressure sleeve 16.

With the exception of a small annular contact area, an air gap 20 is arranged between the end shield 1 and the friction disk 22, so that the thermal contact resistance from the friction disk 22 to the end shield 1 is increased.

The second brake can be released manually using a lever 21. This means that the spring force of the springs pressing on the armature disk can be overcome without energizing the brake coil.

The housing of the electric motor is protected by an in 1 not shown, on the output side, the end shield accommodating the further bearing of the rotor shaft 3, the stator housing part 29 accommodating and surrounding the stator laminated core and the end shield 1 accommodating the bearing 2 are formed by providing tie rods passing through these three parts and by means arranged on the axial end regions of the tie rods 23 Nuts are fixed against each other.

A protective cap 28, preferably made of plastic, is arranged on the axial end region of the stator housing 29 facing the end shield 1. In this way, the spatial area of the first brake is separated from the interior area of the motor. The protective cap 28 creates such a seal that brake pad abrasion cannot get into the engine interior area. The rotor shaft 3 is passed through the center through the protective cap 28, the protective cap 28 having a gap sealing region 35 facing the rotor shaft 3. In order to create a long axially extending gap, the protective cap 28 is further expanded in the axial direction at a first radial distance than at a second radial distance, the second radial distance being greater than the first radial distance.

The protective cap is connected to the axial end region of the stator housing 29 in a non-positive and/or positive manner.

As in 9 Shown more clearly, the stator housing has an inner bore that accommodates the stator laminated core, at the axial end region of which the protective cap 28 is attached. A section 90 of the protective cap 28 inserted into the inner bore is elastically deflected in the radial direction and thus presses on the inner wall of the inner bore of the stator housing 29 which accommodates the protective cap 28.

The protective cap 28 extends radially from the gap to the rotor shaft 3 over the radially covered area of the stator laminated core.

An air gap 34 is arranged between the friction disk 26 and the protective cap 28, so that a thermal barrier is implemented in this area, which makes heat conduction from the spatial area of the first brake to the engine interior area more difficult.

A gap 36 is arranged between the driver 27 connected to the rotor shaft 3 and the end shield 1, which, however, is so small that brake abrasion essentially cannot penetrate into the engine interior area. In addition, the rotor shaft has a shoulder in the area of the first brake, so that any brake abrasion that may occur is thrown off the associated edge. The edge is axially close to the entry area of the rotor shaft into the end shield 1.

At the axial end region of the rotor shaft 3 facing away from the output side of the motor, a fan 17 is arranged, the cooling air flow of which comes from the Fan cover 9 is guided and emerges through outlet openings on the end shield 1 between the fan cover 17 and end shield 1 and then substantially axially along the axially extending cooling fins 38, which are arranged on the outer circumference of the end shield.

The first brake, which is arranged inside the engine interior, is therefore pre-assembled on the magnet body 43 by the guide bolt 25, the screw 42, in particular the countersunk head screw, fixing the guide bolt 25 on the magnet body 43. The pre-assembled and thus pre-completed first brake is then inserted into the end shield 1 and screwed on from the B side using the screw 41 to connect the magnetic body 43 to the end shield 1. The B side is the side axially facing away from the output side of the motor.

In the next step, the protective cap 28 is also pressed into the recess from the B side and connected. After installing the first brake in the motor and tightening the tie rods 23, the second brake is mounted on the end shield 1, in particular fixed with the stud screws 19.

In the exemplary embodiment according to 2 and 3 Instead of the guide bolt 25 and the screw 42, a guide bolt 202 is used, which can be screwed with a threaded area into a corresponding internal thread of a threaded hole in the magnet body 43. Towards the A side, i.e. the driving side of the motor, the guide bolt 202 has a central recess , in which a hexagon socket is inserted. In this way, the guide bolt 202 can be screwed into the magnet body 43 using a hexagonal tool. A screw 201 can be screwed into a threaded area located axially deeper in the central recess of the guide bolt 202 and presses the friction disk 26 onto the guide bolt 202 with its screw head, in particular the countersunk screw head. For centering, a corresponding depression is incorporated into the friction disk 26, into which the guide pin 202 is inserted.

In the exemplary embodiment according to 4 and 5 Instead of the guide bolt 25 and the screw 42, a guide bolt 401 is used, which can be screwed with a threaded area into a corresponding internal thread of a threaded hole in the magnet body 43. Towards the A side, i.e. the driving side of the motor, the guide bolt 401 has an external hexagon. In this way, the guide bolt 401 can be screwed into the magnet body 43 using a hexagon socket tool. A central recess of the guide bolt 401 has a threaded area and thus a screw 402 can be screwed in, which presses the friction disk 26 onto the guide bolt 401 with its screw head, in particular the countersunk screw head. For centering, a corresponding counterbore is incorporated into the friction disk 26, into which the guide pin 401 is inserted.

In the exemplary embodiment according to 6 and 7 Instead of the guide bolt 25 and the screw 42, a pressure sleeve 602 is used, which is inserted into a corresponding hole in the magnet body 43, so that a collar of the pressure sleeve 602 rests on a pole face of the magnet body 43. By means of the screw head, in particular the countersunk screw head, of the screw 603, the friction disk 26 is pressed onto the magnetic body 43 via the pressure sleeve 602. An O-ring 601 arranged on the outer circumference of the pressure sleeve 602 serves to dampen the shock load of the play-affected guide of the armature disk 24. The pressure sleeve 602 is pressed onto the magnet body 43 by means of the screw 603, in particular a countersunk screw, the screw 603 being inserted into a threaded hole in the magnet body 43 is screwed in.

In the 2 until 7 the respective guide pin or the respective pressure sleeve has a jump in diameter, so that the corresponding collar rests on a flat surface which corresponds to the countersink assigned to the threaded hole in the magnet body.

Reference symbol list

1

Bearing shield

2

camp

3

Rotor shaft

4

taker

5

Spring element to suppress play in the driving teeth 11

6

Brake coil

7

Coil carrier

8th

Magnetic body, especially cast steel part

9

Fan cover

10

shaft seal

11

Driver gearing

12

Pad carriers, especially double disc pad carriers

13

Armature disc

14

brake pad

15

Spring element, in particular compression spring

16

pressure sleeve

17

Fan

18

Adjusting nut for adjusting the air gap

19

Stud screw part

20

air gap

21

Hand release lever

22

friction disc

23

Tie rods

24

Armature disc

25

Guide pin

26

friction disc

27

taker

28

protective cap

29

Stator housing

30

Winding head, deflection areas of the stator windings

31

Coil carrier

32

rotor

33

Brake coil

34

air gap

35

The gap sealing area of the plastic cap 28 facing the rotor shaft

36

Gap between driver 27 and end shield 1

37

Brake disc, especially pad carrier

38

cooling fins

39

Coil carrier

40

Sealing part

41

Screw for connecting the magnet body 43 to the end shield 1

42

Screw, especially countersunk head screw

43

Magnetic body

90

elastically radially deflected section of the protective cap 28

201

screw

202

Guide pin

401

screw

402

Guide pin

601

O-ring

602

pressure sleeve

603

Screw, especially countersunk head screw

Claims (11)

Electric motor with a redundant brake arrangement, the electric motor having a bearing plate (1) which is connected to a housing part and/or the stator of the electric motor, the bearing plate (1) receiving a bearing (2) of the rotor shaft (3) of the electric motor, wherein a first and a second electromagnetically actuated brake are mounted on a bearing shield (1) of the electric motor, the first brake being arranged on a first side of the bearing shield (1) and the second brake being arranged on the other side of the bearing shield (1). , characterized in that the end shield (1) is pot-shaped, the pot bottom being arranged on the axial side of the pot facing away from the stator, with a recess on the pot bottom of the end shield in a thickening of the pot bottom that rises towards the stator, in which the bearing (2) of the rotor shaft (3) is accommodated. wherein the friction disk (26) of the first brake is screwed to the magnetic body (43) of the first brake by means of a screw via a pressure sleeve (602), namely via a pressure sleeve (602) which acts as a guide pin (25), the pressure sleeve (602 ) guides the armature disk (24) in the axial direction, the screw protruding through the pressure sleeve (602), the pressure sleeve (602) being arranged between the friction disk (26) and the magnetic body (43), the magnetic body (43) having a bore , into which a pressure sleeve (602) is at least partially inserted, the friction disk (26) being pressed by means of a screw over the pressure sleeve (602) towards the magnet body (43), an O-ring (601) being placed on the pressure sleeve (602 ) is provided and/or an O-ring (601) is arranged between the pressure sleeve (602) and the armature disk (13, 24). electric motor Claim 1 , characterized in that the housing part accommodates the stator windings and has a recess on its side facing the end shield (1), which is covered by a protective cap (28), i.e. a plastic protective cap (28), wherein the protective cap (28) has a recess for the passage of the rotor shaft (3), the protective cap (28) being designed to be axially widened towards its smallest radial distance in order to form a gap seal towards the rotor shaft (3), the bearing plate (1) being radial outside the radial distance area covered by the protective cap (28), the housing part touches and / or is connected to the housing part, the protective cap (28) having a shoulder with which it is held in a non-positive manner on the housing part or the edge of the recess. Electric motor according to at least one of the preceding claims, characterized in that each brake has an electromagnet and an axially movable armature disk (13, 24) which is arranged in a form-fitting manner with or without play in the circumferential direction and which axially extends towards the respective electromagnet when the electromagnet is energized is moved against the spring force of a respective spring element and which, when the electromagnet is not energized, is pressed by the respective spring element (15) onto a brake pad carrier, which is thus pressed onto a braking surface of a friction disk (22, 26). Electric motor according to at least one of the preceding claims, characterized in that the lining carrier (12) of the first and/or the second brake is axially movable but non-rotatable with the rotor shaft (3) of the electric motor or with a driver part which is non-rotatable with the rotor shaft (3 ) is connected, wherein the lining carrier (12) has an internal toothing which engages with an external toothing of the rotor shaft (3) or the driver part, the driver part being connected to the rotor shaft (3) by means of a feather key connection, and / or that the internal toothing and/or the external toothing is an involute toothing, and/or that a spring element (5) is arranged between the internal toothing and/or external toothing to reduce or suppress play. Electric motor according to at least one of the preceding claims, characterized in that the first brake is arranged on the axial side of the end shield (1) facing the stator and the second brake is arranged on the axial side of the end shield (1) facing away from the stator. Electric motor according to at least one of the preceding claims, characterized in that an at least partially axially extending air gap (20, 34) is arranged between the end shield (1) and the driver part of the first brake. Electric motor according to at least one of the preceding claims, characterized in that the end shield (1) is held together with the housing part and/or stator of the electric motor by means of tie rods (23). Electric motor according to at least one of the preceding claims, characterized in that the magnetic body (8, 43) of the first brake is screw-connected to the end shield (1), the screws being from the side of the end shield (1) facing away from the stator, i.e. the pot bottom of the End shield (1) is screwed in. Electric motor according to at least one of the preceding claims, characterized in that the housing part accommodates the stator windings and has a recess on its side facing the end shield (1), which is covered by a protective cap (28), i.e. a plastic protective cap (28), wherein the protective cap (28) has a recess for the passage of the rotor shaft (3), the protective cap (28) being designed to be axially widened towards its smallest radial distance in order to form a gap seal towards the rotor shaft (3), the air gap (20, 34 ) between the rotor shaft (3) and the protective cap (28) is smaller than an average-sized abrasion particle that falls off the friction lining during braking, the end shield (1) touching and/or with the housing part radially outside the radial distance area covered by the protective cap (28). is connected to the housing part, the protective cap (28) having elastic regions deflected inwards in the radial direction from the recess, so that the protective cap (28) is held non-positively on the recess, the protective cap (28) having a shoulder with which it is held non-positively on the housing part or the edge of the recess. Electric motor according to at least one of the preceding claims, characterized in that the rotor shaft (3) has a shoulder, i.e. a circumferential edge, which is arranged axially next to the axial region covered by the protective cap (28) for throwing off abrasion particles before they enter the intermediate Rotor shaft (3) and protective cap (28) arranged gap seal. Electric motor according to at least one of the preceding claims, characterized in that a fan (17) is arranged on the axial end region of the rotor shaft (3), the cooling air flow of which is directed along the second brake and along axially extending cooling fins, the cooling fins being on the outside of the End shield are arranged and are made in one piece with the end shield (1).

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