GB2495713A

GB2495713A - DC brush motor for driving a cooling system fan

Info

Publication number: GB2495713A
Application number: GB1117868.8A
Authority: GB
Inventors: Ramon Grau; Guillermo Sancho; Joan Garriga; Julien Algret
Original assignee: Nidec Motors and Actuators Germany GmbH
Current assignee: Nidec Motors and Actuators Germany GmbH
Priority date: 2011-10-17
Filing date: 2011-10-17
Publication date: 2013-04-24
Also published as: GB201117868D0

Abstract

An electric brush motor for driving a fan of a cooling system comprises a rotor (fig 2, 30) and a commutator 36 on a shaft 32 mounted in a housing 50 that comprises an air inlet and an air outlet. A brush 66 and commutator 36 are arranged behind an armature 34 of the rotor in an air flow generated from the inlet to the outlet. The air outlet, brush and comutator can be in a front cover 52 of housing 50 which can comprise a rear cover (fig 2, 80). Brush 66 can be supported in a brush cage 64 that is directly mounted in a housing 50 having a bowl-shaped portion comprising a base 52 and a wall 54.The bowl-shaped housing can be made from a plastics or polymeric material and have metal sheets 42, shaped in half rings, at the housing lateral wall. A spacer 545 can keep an air gap between brush cage 64 and base 52. The lateral wall can have a brush cage support (fig 4, 547) comprising a groove to receive a protrusion (fig 5, 647) of the brush cage. Metal sheets 42 can be insulated from each other and connected to different potentials of the motor. Fan can have a hub (fig 6, 91) protecting the motor and cooling ribs (fig 6, 92) to generate the air flow in the motor.

Description

Titel: New engine cooling architecture motor [0001] The present disclosure relates to electric DC brush motors. The present invention relates in particular to protected electric DC brush motors exposed to different environment conditions that are used for example in cooling systems of motor vehicles.

[0002] Electric DC (direct current) brush motors have a wide range of applications in to modern technology. One particular application is the use of electric DC brush motors for driving a fan of a car engine cooling system. These car engine coofing systems usually comprise a liquidJair heat exchanger that is cooled by an air flow. In some instances the air flow is generated or accelerated using a fan driven by a DC brush motors. The electric DC brush motor is in many examples arranged in front or behind the heat exchanger. Similar cooling systems are used in electric vehicles or in hybrid vehicles. The electric DC brush motors are usually placed in the centre of the fan which is directly mounted on the shaft of the electric DC brush motor. Examples for these dectric DC brush motors and their arrangement at the heat exchanger can be found in most of the cars distributed today.

[0003] Electric DC brush motors for these applications have to withstand a wide range of temperatures and air humidity and are often exposed to dirt or dust conditions. The electric DC brush motors have to work reliable under these conditions over extended periods of time to avoid overheating of the car systems in hot conditions.

[0004] State of the art electric DC brush motors comprise a rotor with an armature and a commutator mounted on the shaft. The rotor is rotatably supported by usually two beanngs inside a metal housing. The metal housing is of cylindrical shape and has a front end cover and a rear end cover closing the housing at its axial ends. A stator is arranged inside the metal housing and separate brush card is atTanged at the rear end cover side holding the brushes that interact in use with the commutator.

[0005] Electric DC brush motors have to be cooled by an air flow due to the heat losses generated mainly by the armature. It is important to cool the brushes and the armature in a

I

continuous manner. State of the ai-t motors therefore comprise air inlet holes in the rear cover to let a cooling air flow pass from the air entry holes over the brushes on the brush card and over the armature to exit holes at the front cover. The term front cover defines the side of the electric DC brush motor, at which the fan is mounted onto the shaft. The fan generates and air flow for cooling the heat exchanger of the car cooling system. The air flow is also used for the interna' cooling of the electric DC brush motor. In know systems, the air flows for internal cooling and for cooling the heat exchanger flow in the same direction.

[0006] Hot corrosion of electrical contacts and the brushes is considered an important issue for reliability of the electnc DC brush motor. To avoid hot corrosion, the brushcard is arranged at the opposite side of the fan in state of the art electric motors. The brushes and the commutator are directly exposed to air pollution, humidity and other environmental constraints.

[0007] US 2006/0239838 gives an example for an electric DC brush motor that can be used for engine cooling. The iotor and the brush support al-c mounted in a housing integrated in the shroud structure in order to minimize the number of elements used.

[0008] It is an object of the car industry and electric DC brush motor industry to reduce manufacturing costs and the number of elements used in the manufacture of electric DC brush motors. It is also object to increase the reliability of these electric DC brush motors.

Summary of the invention

[0009] The present disclosure suggests an electric motor comprising a rotor arranged on a shaft and rotatably mounted in a housing The housing comprises an air inlet and an air outlet. When the motor is in use, an air flow is generated from the air in'et to the air outlet and at least one brush is arranged behind the armature in the air flow. The electric motor may thus be termed an electric brush motor. The electric motor may be a DC (direct current) motor and may be termed DC motor or DC brush motor. In other words, the air inlet is at the armature side of the housing and the air outlet is at the brush/commutator side of the housing. While at least one brush is arranged behind the armature, it is obvious to a person skilled in the art that least two brushes are necessary to drive the electric motor.

[0010] Surprisingly and in contrast to common knowledge of a person skilled in the art, it has been found that the inverse arrangement of the brushes and the rotor -in particular of the armature of the rotor -does not affect hot corrosion or liability of the electric DC brush motor. This is in contrast to the general expectation of a person skilled in the art. The inverse arrangement in the air flow has a number of advantages. It allows a cheaper protection and a more compact housing of the electric DC brush motor and more efficient cooling.

[0011] The rotor of the electric DC brush motor may comprises an armature and a commutator arranged on shaft. The shaft, the armature and the commutator may be as known in the art. As the brushes are arranged on the front side behind the armature in the air flow the commutator is arranged on this side as well.

[0012] The housing of the electric DC brush motor may comprise a fl-out cover and a rear cover and the at least one brush may be arranged at the front cover of the housing.

Mounting the brushes directly at the front cover side of the housing allows omitting a separate brush card or integrating the brush card into the housing. No separate mounting of the brush card in the electric DC brush motor is required and the number of parts is reduced.

[0013] The front cover may also comprise the air outlet: the air flow passing the brushes and the commutator is directly blown out of the electnc DC brush motor. Dust from brush wear is directly transported to the outside of the electric DC brush motor.

[00141 The front cover and the rear cover may support bearings of the shaft. The term front cover and rear cover may be understood with respect to the fan. The fan is mounted on the front cover side and the shaft extends out of the front cover side.

[0015] At least one part of the housing may be bowl-shaped. The bowled shaped part may substantially have a bottom section and a cylindrical lateral surface. The bottom section may be the front cover of the electric DC brush motor housing. The bottom part may comprise the air outlet. The air outlet, however, can be alTanged at the cylindrical lateral side or another place on the bowl-shaped part.

[001 6] The bowl-shaped part may be made from a plastic material and may be injection molded. A particular advantage is that the brushes can be directly arranged at the bottom section i.e. at the front cover of the bowl-shaped part. This reduces the number of parts needed for assembling the electric DC brush motor, in particular if the bowl-shaped part is made in one piece.

[00171 The housing may also comprise a cover. The cover may simply cover the bowl-shaped part and may be considered as the rear cover of the electric DC brush motor. The rear cover may be made from a plastic material.

[001 8J The housing of the electric DC brush motor may be supported by at least one arm.

The at least one arm may comprises an air guiding channel for guiding air into or out of the housing.

[0019] The air guiding channel may be connected to an air inlet of the housing of the electric DC brush motor. The front cover may comprise air outlet. Alternatively or in combination plurality of arms with air guiding channels may be provided. A first arm can be used as an air inlet and a second arm may be used as air outlet. In this case the housing can be otherwise completely sealed which allows the use in wet environments and under wet or dust conditions.

[0020] The present disclosure also relates to an electric DC brush motor comprising a rotor arranged on a shaft and rotatably mounted in a housing. A plurality of brushes may be arranged directly at the front cover side of the housing. The front cover may thus be used as brush card and a conventional brush card can be omitted.

[0021] The present disclosure also relates to an electric DC brush motor comprising a rotor arranged on a shaft and rotatably mounted in a bowl-shaped housing portion. The bowl-shaped housing portion comprises a base and a lateral wall, wherein at least one brush is supported in a brush cage directly mounted to the bowl-shaped housing portion. The base of the bowl-shaped housing portion may be the front cover and the lateral wall may have substantially cylindrical shape. Mounting the brushes in a brush cage directly to the bowl-shaped housing allows omitting a conventional brush card. It is possible to use longer brushes which increases the lifetime of the electric motor.

[0022] A gap may be provided between the brush cage and the front cover. The gap or air channel allows an air flow to pass between the front cover an the brush cage which enables efficient cooling of the brushes. The brush cage may comprise at least one spacer element keeping the brush cage at a distance from the base. The lateral wall may comprise at least one brush cage receiving section for receiving and supporting the brush cage. The brush cage receiving section may interact with a corresponding brush cage fixation in the brush.

The interaction of the brush cage receiving section with the brush cage fixation maintains the brush cage fixed in the bowl-shaped housing.The spacer may be used to additionally support the brush cage. For example the at least one brush cage receiving section may comprise a groove and the brush cage may comprise a corresponding protrusion or vice versa. The groove and the protrusion may interact without substantial tolerance to fix the brush cage if inserted in the groove. The groove and protrusion may allow an axial movement with respect to the shaft to allow easy assembly.

[0023] The brush may be movable inside the brush cage along a longitudinal direction of the brush cage. The brush may be biased along the longitudinal direction towards the shaft of the electric motor to ensure electric contact with the commutator. The longitudinal direction of the brush cage may be arranged radially to the shaft. Alternatively, the longitudinal direction of the brush cage may be arranged in an angle with respect to the radial direction. The arrangement in an angle with respect to the longitudinal direction reduces vibrations of the brushes.

[0024] The present disclosure also relates to an electric brush motor comprising a rotor alTanged on a shaft and rotatably mounted in a bowl-shaped housing portion. The bowl-shaped housing may be made from a polymeric material and at least one metal sheet is arranged in at least one portion of the bowl-shaped housing. The metal sheet allows radio frequency shielding, flux circulation, fixation of magnets and enables in the same time the use of inexpensive polymeric material for forming the housing. This is in particular useful with more complex housing shapes, such as a bowl-shaped housing. The bowl-shaped housing can be made from one single piece, for example by injection molding. In one aspect, the metal sheet may be electrically connected to a ground potential.

[0025] The bowl-shaped housing may comprise a base and a lateral wail of for example cylindrical shape and the metal sheet may be arranged at the lateral wall. The at least one metal sheet may have the shape of a ring section, arranged circumferentially around an armature of the electric motor. it has been shown that this arrangement is sufficient to obtain RFI (radio frequency interference) shielding. RFI may be even more reduced if at least two metal sheets in form of half rings are used that may be connected to different electrical potentials of the electric motor.

[0026] The metal sheet may be arranged at the inner side or inside the lateral wall to ensure isolation of the metal sheets.

[0027] It will be understood that a person skilled in the art will combine the features of the present disclosure and that not all features described have to implemented in an electric motor.

Descriptioi of the figures

[0028] The following description of examples of the invention may be better understood with respect to the accompanying drawings of examples of the invention, in which: [0029] Figure 1 shows an example of the arrangement of an electric motor driven fan in a cooling system of a car; Figure 2a shows a conventional electric DC brush motor and figure 2b shows an example of the present invention; Figure 3 shows a cross-section of an electric DC brush motor of the present disclosure; Figure 4 shows the assembly of a metal sheet of the present disclosure; Figure 5a and 5b show the alTangement of the brushes in the housing of the present

disclosure; and

Figure 6a to 6c show a fan that may be used with the present invention.

Detailed description

[0030] The following detailed description gives examples of how the present disclosure may be implemented. While several features of the present disclosure are implemented in the described examples it is to be understood that the invention is not limited to those combinations and that a person skilled in the art will select those features that are appropriate for a specific application.

[0031] Figure 1 shows a front part of a car in which an electric fan 9 is held by a shroud behind a heat exchanger 105. The car 100 has a driving direction 101 and all directions given herein will refer to the dnving direction 101 of the car. The heat exchanger 105 of a cooling system is arranged in front of a motor block 104. The cooling system and the evaporator 105 may be a water based cooling system as known in the art. Any other refrigerant may be used instead of water. The heat exchanger 105 may be an air/liquid heat exchanger that is cooled by an external air flow 102 which may arise when the car is moving. This external air flow 102 crosses the air liquid heat exchanger 105 and cools the liquid inside the heat exchanger 105. If the air flow generated by the movement of the vehicle 100 is not sufficient, a fan 9 may be actuated in order to accelerate the external air flow 102. The fan 9 may be alTanged behind the heat exchanger 105 in the external air flow 102, as shown in the example of Figure 1. In other words the external air flow 102 first passes the heat exchanger 105 and subsequently the fan 9. The fan 9 is driven by an electric motor 10 which holds the fan on its shaft. A shroud structure 500 holds the electric motor and thereby the fan 9 in place and provides some protection from the turning fan 9.

This structure is known in the art and used in many vehicles. While the further description refers to this particular arrangement of the heat exchanger 105, fan 9, electric motor 10 and shroud 500, other arrangements are possible as well. For example, the fan 9 and the electric to motor 10 can be arranged on the front side of the heat exchanger 105 thus blowing the air through the heat exchanger, and/or the heat exchanger. fan and electric motor can be arranged differently with respect to the driving direction 101 of the car 100.

[0032] Figure 2a shows a conventional electric DC brush motor that is used to date in a is vehicle shown in Figure 1. The conventional motor 1 comprises a front cover 2, a rotor 3 with an armature and a commutator mounted on a shaft. The rotor 3 is arranged in a stator housing which supports stator magnets. A brush plate 6 supporting the brushes iii position and providing the electrical connection 7 is inserted in the stator housing 4 and covered by a separate rear cover 8.

[0033] The rear cover 8 and the front cover 2 comprise a lear bearing and a front bearing which the shaft is rotatable supported. An air flow is guided through the rear plate 8 over the brushes on brush plate 6, through the commutator 36, and through air outlet holes in front cover 2. This standard configuration is not optimizing brushcard components and commutator protection against external pollution and the air flow through the dectric motor 10 is a portion of the external air flow 102 passing through the heat exchanger 105.

[0034] Figure 2b shows an example of the present disclosure. The housing of the electric DC brush motor 10 comprises a bowLshaped part or portion 50 and a rear cover 80. The rear cover 80 closes the bowl-shaped portion 50 thereby forming the entire housing of the electric DC brush motor 10. A rotor 30 with an lamination stack 34, a commutator 36 arranged on a shaft 32, and a is placed inside the bowl-shaped portion 50. As can be seen from figure lb, the assembly of the electric DC brush motor 10 may be reduced to oniy three parts whereof at least the bowl-shaped portion 50 can be largely preassembled. The details of the bowled shaped portion 50 will be explained in detail below.

[0035] The lamination stack 34 may comprise windings as known in the art.

[0036] Figure 3 shows an example of an electric DC brush motor 10 of the present disclosure in a cross-sectional view. The rear cover 80 is omitted to show the interior of the electric DC brush motor. The electric DC brush motor comprises a bowl-shaped housing tO part 50 made from a plastics material, which can be, for example injection molded. The bowl-shaped part 50 essentially comprises a cylindrical lateral wall 54 and a bottom cover or front cover 52.

[0037] A front cover bearing 23 is arranged at a centre portion of the bottom cover or front cover 52. As illustrated in the example, the cover bearing 23 can be embedded in the commutator 36. The front cover bearing 23 rotatably supports a shaft 32. A second bearing 83 can be mounted in the rear cover 80 for rotatably holding the shaft 32. The commutator 36 and an armature 34 are arranged on the shaft 32 as generally known in the art. The armature 34 and the commutator 36 can be mounted by any means known to a person skilled in the art. It is to be noted that the commutator 36 is arranged on the front cover side 52 and the armature 34 is arranged at the rear cover 80 side of the electric DC brush motor 10.

[0038] The electric DC brush motor 10 comprises a stator which comprises in the assembly of metallic yoke ring 42 and magnet 40. The magnet 40 can be for example a permanent magnet alTanged circumferentially around the armature 34. A plurality of stator magnets 40 may be used. For example four magnets may be arranged on the inner side of the metallic yoke ring 42. Any other number of magnets 40 may also be used. The metallic yoke ring 42 may be arranged circumferentially around the permanent magnets 40. In particular the permanent magnets 40 may be glued or otherwise fixed onto the metallic yoke ring 42. The metallic yoke ring 42 has several functions: -fixing the magnets 40 -allow flux circulation -avoid RFI (radio frequency interference) emissions (shield) Steel maybe used as material. The meta'lic yoke ring 42 may be an assembly of two half rings 42a, 42b used as will be described in the figure 4.

[0039] Brushes 66 are mounted close to the base or front cover 52 at the cylindrical atera1 waIl 54 of the bowl shaped portion 50. The bowl shaped portion 50 can be made from an injection molded plastic material. The brushes 66 are mounted in a brush cage 64 which is arranged directly on the cylindrical lateral wall 54. There is no need to use a separate brush card as previously done. Other electric elements such as fuses, chokes, thermal switches or other elements usually arranged at the brushcard may be arranged on the front cover 52.

Brush braids or contacts can be welded on front cover 52.

[0040] The front cover 52 may comprise one or more openings 28 through which a cooling air flow may be evacuated and that may be termed outlet openings 528. The outlet openings 528 are arranged in proximity to the brushes 64. The cooling air flow passing and cooling the brushes is subsequently evacuated through the outlet opening 528. The air outlet holes 528 may face towards the side in which the fan 9 is arranged on shaft 32 and thus opposite to the direction of the external air flow 102 if the fim 9 is arranged behind the heat exchanger as shown in Figure 1.

[0041] Electric connections 70 may be integrated inside the injection molded bowl-shaped part 50 of the housing. Over molding may be used to insolate the electnc contacts 70. The over molding of the electric contacts 70 allows to avoid specific isolation of the electric contacts. The over-molding also enaNes save guiding of the electrical currents towards the brushes 66 and the over-molded trimmed sheet 76. The electnc contacts comprise a positive 70a and a negative 70b electrical contact, which are electrically isolated with respect to each other.

[0042] Figure 4 shows how the meta' ling 42 may be assembled in the bowl-shaped part 50 of the housing. The metal ring 42 may comprise two halves 42a and 42b that are separate elements and arranged electrically isolated with respect to each other. -Il-

[00431 The metallic half rings 42a. 42b may be inserted inside the cylindrical lateral wall 54 of the bowl-shaped portion 50. In the example shown, the cylindrical lateral wall 54 may have an upper cylindrical portion 544 and a lower cylindrical portion 546. The lower cylindrical portion 546 has a smaller inner diameter than the upper cylindrical portion 544, thereby providing a step 545. The inner diameter of the upper cylindrical portion 544 is sufficiently wide to sulTound the half rings 42a, 42b and to leave an air gap between the stator magnets 40 and the armature 34.

[0044] The step 545 may provide an axial stop and a support for the metallic half rings 42a, 42b. when mounted into the bowkshaped portion 50. At least two contact elements 74a and 74b are integrated in the step 545 and come into electric contact with a lateral suiface of each one of the metallic half rings 42a and 42b. respectively. The contact elements 74a and 74b may be in electrical contact with the electric connection 70a, 70b.

This allows electrical decoupling of metallic half rings 42a, 42b which significantly enhances shidding of radio frequencies. Positive and negative electrical terminals are connected to two separated giounds. The lower cylindncal portion 546 may also comprise reception portions 547 for holding and securing the brush cages 64. Thereby the brush cages can be extended to a maximum length which allows to use longer brushes which increases the live time of the electric DC brush motor.

[0045] Figures 5a and Sb show the arrangement of the brush cages 64 and the brushes 66 in more detail. Figure Sa shows a cross sectional view through the brush cage 64 with a brush 66 arranged at the bottom of cylindrical lateral wall 54 of the bowl-shaped portion 50. Figure Sb shows a top view from above looking onto the bottom cover 52.

[00461 The brush cage 64 has a cage like structure in which the brush 66 is supported and guided in a longitudinal direction. The brush 66 is allowed to move in the longitudinal direction an is biased towards the commutator 36, as known in the art. The longitudinal direction may be essentially the radial direction with respect to the rotational axis of the motor 10. As shown in Figure 4b, the longitudinal axis may also be arranged at an angle to the radial axis. This angle allows to considerably reducing vibrations and thereby noise generated by the electric DC brush motor.

[0047] The brush cage 64 has a fixation end 647 which interacts with the colTesponding brush reception portion 547 to hold the brush cage in a predetermined position. The brush cage 64 further has a shidd portion 643 arranged towards the commutator 36 to locate a brush spring.

[0048] The brush cage 64 is arranged direcfly on the bottom of cylindrical lateral wall 54, as shown in figure 4a. The brush cage 64 is supported by a protrusions 526 formed in the bottom of cylindncal lateral wall 54. These protrusions support the brush cage at extremity only and leave an air gap between the bottom surface 52 and the brush cage 64 in other areas. The brushes 66 may therefore be termed as flying brushes. This air gap allows a cooling air flow to pass and ensures cooling of the brushes 66.

[0049] Figures 6a and 6b show a fan 9 that may be used with the electric DC brush motor i 0 of the present disclosure. Figure 6a shows an electric DC brush niotor 10 arranged and attached to the fan 9. Figure 6b shows the fan without electric DC brush motor. The fan has an inner housing 91 called hub in which the electric DC brush motor 10 is arranged and which protects the electric DC brush motor 10. A plurality of blades 93 are arranged on the outer surface of the inner housing 91 and are in contact with an outer ring 95. The outer ring 95 of the fan 9 may be adapted to fit in a shroud structure of a cooling system as known in the art. The cooling ribs 92 generate an air flow in the electric DC brush motor 10. When the electric motor and consequently the fan 9 is rotating, the cooling ribs 92 generate a depression and an air flow out of the inner housing 91. Mternatively or in addition, the external flow 102 generates a depression by the well known Venturi effect for evacuating the hot air of the inner flow out of the inner housing 91.

[0050] The electric DC brush motor 10 may have arms 56 for supporting the electric DC brush motor. The arms 56 may be arranged on the cylindrical wall 54 of the bowl-shaped portion 50. The arms 56 may be integrally formed or may be separate arm elements attached to the bowl-shaped portion 50. The arms 56 are designed to support the electric DC brush motor 10 and a fan 9 attached to it, if the electnc DC brush motor is used for example in a car cooling system. The arms 56 may be attached to a shroud structure as generally known in the art. Usually a plurality of arms 56 is used to support the electric DC brush motor. The example shown in figures 7a applies in total five arms 56 but any other number of arms may be used as well.

[0051] It should be understood that the examples of the present disclosure given above are purely illustrative and that feature described in the examples can be combined in any way.

For example. a person skilled in the art may combine the brush cages described with respect to figure 5 with the motor housing descnbed with respect to figures ito 4. Features at the metallic yoke ring and the contacts may also be combined or used separately.

Claims

<claim-text>Claims I. An electric DC brush motor (10) for driving a fan (9) of a cooling system, the electric DC brush motor (10) comprising a rotor 30) and a commutator (36) arranged on a shall (29) and rotatably mounted in a housing, the housing (50) comprising an air inlet (82; 566) and an air outlet (528; 566), and wherein in use an air flow is generated from the air inlet (82; 566) to the air outlet (528; 566) and wherein at least one brush (66) and the commutator (36) are arranged behind an armature (34) of the rotor in the air flow.</claim-text> <claim-text>2. The electnc DC brush motor (10) of claim 1, further comprising a front cover and a rear cover arranged on both sides of the rotor, wherein the at least one brush and/or a commutator are arranged at the front cover of the housing.</claim-text> <claim-text>3. The electric DC brush motor (10) of claim 2, wherein the air outlet is arranged in the front cover (52).</claim-text> <claim-text>4. The electric DC brush motor (10) of any one of claims ito 3. wherein the housing is composed of a substantially bowl-shaped portion (50) and a lock portion (80), wherein the bowl-shaped portion (50) comprises the front cover (52) as a base and wherein the lock portion (80) comprises the rear cover.</claim-text> <claim-text>5. The electric DC brush motor (10) of claim 4, wherein the substantially bowl-shaped portion (50) comprises the air outlet (528).</claim-text> <claim-text>6. The electric DC brush motor (10) of claim 4 or 5. wherein at least the bowl-shaped part is made from a plastics materiaL 7. The electric DC brush motor (10) of any one of claims 2 to 6, wherein the rear cover (80) is made from a plastics material.8. The electric DC brush motor (10) of any one of the preceding claims, wherein at least one brush (66) is arranged in a brush cage (64) mounted on the bowl-shaped portion (50).9. The electric DC brush motor of claim 8, further comprising an air gap between the brush cage and the front cover.10. An electric brush motor (10) for driving a fan (9) of a cooling system, the electric motor (10) comprising a rotor (30) arranged on a shaft (29) and rotatably mounted in a bowl-shaped housing portion (50), wherein the bowl-shaped housing porion (50) comprises a base (52) and a lateral wall (54), and wherein at least one brush (66) is supported in a bi-ush cage (64) directly mounted to the bowl-shaped housing portion (50).11. The electric brush motor (10) of claim 10, further compnsing an air gap (65) between the brush cage (64) and the base (52) of the bowl-shaped housing portion (50).12. The electric brush motor (10) of dairn 10 or II, wherein the brush cage (64) comprises at least one spacer element 545) keeping the brush cage(64) at a distance from the base (52).13. The electric brush motor (10) of any one of claims 10 to 12, wherein the lateral wall (54) comprises at least one brush cage receiving section (547) for receiving and supporting the brush cage (66).I & The electric brush motor (10) of any one of claims 10 to 13, where the at least one brush cage receiving section (547) comprises a groove and the brush cage (66) comprises a corresponding protrusion (647).15. The electric brush motor (10) of any one of claims 10 to 14, wherein the at least one brush (66) is movable inside the brush cage (64) along a longitudinal direction of the brush cage (64) and biased towards the shaft (29) of the electric motor (10).16. The electric brush motor (10) of claim 15, wherein the longitudinal direction is arranged in an angle to the radial direction of the shaft (29).17. The electric brush motor (10) of any one of claims 10 to 16, wherein the bowl-shaped housing portion (50) is injection molded from a polymeric material.18. An electric brush motor (10) for driving a fan (9) of a cooling system. the electric motor comprising a rotor (30) alTanged on a shaft (29) and rotatably mounted in a bowl-shaped housing (50) made from a polymeric material, wherein at least one metal sheet (42; 42a, 42b) is arranged in at least one portion of the bowl-shaped housing portion (50).19. The electric brush motor (lO) of claim 18, wherein the bowl-shaped housing (50) comprises a base (52) and a lateral wall (54).20. The electric brush motor (10) of claim 19, wherein the at least one metal sheet (42; 42a, 42b) is arranged at at least a portion of the lateral wall (54) of the bowl-shaped housing (50).2i. The electric brush motor (10) of any one of claims 18 to 20, wherein the at least one metal sheet (42; 42a, 42b) has the shape of a ring section, arranged circumferentially around an airnature (34) of the electric motor (10).22. The electric brush motor (10) of any one of claims 18 to 21, comprising at least two metal sheets in form of half rings (42a, 42b).23. The electric brush motor (10) of claim 22, wherein the at least two half rings (42a, 42b) are electrically isolated with respect to each other.24. The electric brush motor (10) of claim 23, wherein the at least two half rings (42a.42b) are on connected to different electrical potentials of the electric motor.25. The electric brush motor (10) of any one of claims 18 to 24, wherein the at least one metal sheet (42: 42a. 42b) is arranged the inner side of the bowl-shaped housing.</claim-text>