WO2015197574A1

WO2015197574A1 - Electric machine

Info

Publication number: WO2015197574A1
Application number: PCT/EP2015/064035
Authority: WO
Inventors: Maurad Berkouk; Sebastien Labat; Eric Fournier
Original assignee: Brose Fahrzeugteile GmbH & Co. Kommanditgesellschaft, Würzburg
Priority date: 2014-06-26
Filing date: 2015-06-23
Publication date: 2015-12-30

Abstract

The invention relates to an electric machine (14), in particular an electric motor, of a motor vehicle, having a rotor (52), which is rotatably mounted about a rotor axis (54), a stator (24) and an electronics unit (28), which comprises a connecting device (32). Between the stator (24) and the electronics unit (28) a shielding plate (26), which is electrically connected to a grounds connection (34) of the connecting device (32), is mounted. An electrically conductive contact element (60) is force-locked between the shielding plate (26) and the stator. The invention further relates to a radiator fan (2) of a motor vehicle, in particular the main fan, comprising said electric machine (14).

Description

description

Electric machine

The invention relates to an electrical machine that is part of a motor vehicle. By electric machine, for example, an electric motor is understood to mean a generator.

Motor vehicles with an internal combustion engine exhibit considerable heat development during operation. To hold the operating temperature of the internal combustion engine and also for the operation of an air conditioner, a liquid coolant is usually used, which in turn must be cooled. This is usually done by means of an acted upon by a wind radiator network, which is in heat exchange with the coolant. For example, the coolant is directed into tubes that are incorporated into the radiator network. Since, especially at low vehicle speeds, the airstream for cooling is normally insufficient, it is known, for example, from EP 1 621 773 A1 to use an electric fan by means of which the airstream is amplified.

Such electric motors are often designed in recent times as so-called brushless machines, according to a direct electrical Kontak- tion of a rotor by brushing is not necessary. The rotor can be equipped with permanent magnets that are driven in a rotating magnetic field of the stator. For this purpose, the stator has stator windings which are driven in a corresponding manner to produce a rotating magnetic field. Frequently, in this case, driving methods, for example by means of pulse width modulation (PWM), used, the associated electronics usually by semiconductor circuits with metal oxide field effect transistors (MOSFETs), IGBTs or thyristors can be realized. By means of the pulse width modulation largely freely selectable field shapes and correspondingly also dynamically rotating fields can be designed. Since, in particular when using pulse width modulation in the kHz to MHz range, electrical jump signals are generated which are intended, for example, to simulate a sinusoidal drive characteristic as accurately as possible, the radiation of electromagnetic waves in the region of the windings and the supply lines must be expected.

This electromagnetic effect can act, for example, on the electronics, but also on other units and consumers in the vicinity of the rotating electrical machine, which is generally undesirable. Therefore, the demand for increased electromagnetic compatibility or the lowest possible transmission activity is becoming more and more important. Accordingly, electrical machine are good to suppress noise.

The invention has for its object to provide a particularly suitable electrical machine of a motor vehicle and a radiator fan of a motor vehicle, in which in particular the generation of spurious electromagnetic radiation signals are minimized, and which are suitably comparatively simple, reliable and easy to install.

With regard to the electric machine, this object is achieved by the features of claim 1 and in terms of the radiator fan by the features of claim 10 according to the invention. Advantageous developments and refinements are the subject of the dependent claims.

The electric machine is part of a motor vehicle and suitably part of a Versteilantriebs or a fan. In this case, the fan is preferably used for cooling an internal combustion engine (internal combustion engine). The electric machine is for example a generator, but particularly preferably an electric motor and in particular a DC motor. Preferably, the electric motor is brushless.

The electric machine has a rotor, a stator and an electronics, wherein the stator is energized by the electronics. For example, the electric constructed as a bridge circuit and includes a number of IGBTs, MOS FETs or the like. Conveniently, the structure of the electronics is a B6 circuit. The electronics comprises a connection device which is electrically contacted in the assembled state with an electrical line of the electrical system of the motor vehicle. By means of the connection device there is a current supply to the electronics. The connection device has a ground connection, which in the assembled state is at the electrical potential of the mass of the motor vehicle. In particular, the electrical potential of the ground terminal is equal to the potential of a body of the motor vehicle.

The stator in turn comprises, for example, a winding, by means of which a rotating magnetic field is generated during operation of the electric machine. Preferably, the stator comprises at least three windings, which are contacted by the electronics in a star or delta connection. Here, the electric machine is preferably designed as a brushless DC motor. By means of the rotating magnetic field, the rotor is set in a rotational movement about a rotor axis about which it is rotatably mounted. For example, the rotor has at least one, preferably a number of permanent magnets.

Between the stator and the electronics a shield plate is arranged, which is made of an electrically conductive material. In particular, the shield plate is a stamped bent part or deep drawn from a sheet metal. For example, the shield plate is pot-shaped designed as a tray, and the electronics is in particular at least partially enclosed by means of the shield plate. This protects the electronics against damage. The shield plate is electrically contacted with the ground terminal of the connection device, so that the electrical potential of the shield plate in the operating state corresponds to ground. The shield plate itself is preferably thermally coupled to a heat sink or at least partially shaped in the manner of a heat sink, so that by means of the shield plate, a heat sink against the electronics is created during operation of the electric machine, and thus the electronics is cooled by the release of heat to the shield plate , Between the Schirnnplatte and the stator, a contact element is arranged non-positively. In particular, the contact element is in direct mechanical contact with the shield plate and the stator. The contact element itself is designed to be electrically conductive and, for example, made of a metal. In particular, the contact element is made of a sheet and preferably a stamped and bent part. The contact element is electrically contacted with the shield plate, so that the contact element is also grounded. Likewise, the components of the stator, which are electrically contacted with the contact element, to ground, so that, in particular static, electrical charging of these components of the stator is prevented. Due to the frictional connection between the contact element and the stator and the shield plate assembly is also relatively simple and inexpensive, since, for example, such a connection can be realized by attaching the shield plate to the stator.

Suitably, the contact element has a contact portion, by means of which the frictional connection between the stator and the shield plate is realized. In particular, the contact portion is resiliently configured so that it is elastically deformed during assembly to create the frictional connection. For example, the contact portion is C-shaped, thus has a substantially C-shaped cross-section. In this case, one of the ends of the contact portion bears against the stator and the remaining end bears against the shield plate. When mounting the radius of the contact portion is preferably reduced, the deformation is particularly elastic. In this way, the adhesion between the shield plate and the stator is comparatively inexpensive created.

In a preferred embodiment of the invention, the contact element is attached to the stator, which simplifies assembly. In this case, the contact element is fastened to the stator and, in a further working step, the end plate is also fastened in particular to the stator, wherein preferably the contact element is elastically deformed to produce a frictional connection. Suitably, the contact element is connected by means of a fastening means on a bearing plate of the stator, in particular on a B-side end shield. In this way, mounting on the component to be driven by the electric machine or on the component driving the electric machine is simplified. In particular, the end shield is electrically contacted with the contact element, so that the electrical potential of the end shield is equal to ground. Conveniently, the bearing plate is aligned parallel to the shield plate.

For example, the fastener is a screw, which allows replacement of the fastener. Alternatively, the attachment means is a pin. In the assembled state, a press fit is expediently created between the pin and the stator. Due to the forces acting on the fastener is held on the stator, and thus the contact element attached to the stator. In particular, the pin is in the assembled state at least partially disposed within a recess of the stator shape and / or non-positively.

Suitably, the fastener protrudes through the end shield. In other words, components of the fastener are located on both sides of the bearing plate. As a result, at least a portion of the fastener is within the stator. In other words, the attachment means projects through the end shield into the interior of the stator. For example, the bearing plate comprises a bore, within which the fastening means is at least partially arranged. For example, the fastening means is bent over on the screen plate opposite side of the bearing plate or the like. If a screw is used as a fastener, for example, a nut is rotated on the thread on this page, with the head of the screw on the screen plate facing side of the bearing plate.

Conveniently, the stator comprises an insulating body, which is made for example of a plastic. In particular, the insulating body is made of an electrically non-conductive material, and preferably serves the electrical Insulation of possible windings of the stator. The insulating body is located on the side facing away from the shield plate of the bearing plate, so that the bearing plate between the insulating body and the shield plate is arranged. The insulating body includes a recess extending in particular along the direction which is parallel to the arrangement direction of the fastening means. In the assembled state, at least a portion of the fastening means is disposed within the recess, and in particular a free end of the fastening means.

Appropriately, in this case a positive and / or frictional connection between the insulating body and the fastening means is created. For example, prior to assembly of the fastener, the cross-section of the recess is less than that of the fastener. If a screw is used as a fastener, milled thus when mounting the screw a corresponding thread within the insulating body, resulting in a relatively robust connection. For example, the insulating body has a substantially hollow-cylindrical projection, wherein the recess is formed by means of the central opening of the extension. In other words, the extension is designed substantially sleeve-shaped. In this way, the fastener is guided by means of the extension during assembly, which prevents damage to any other components of the stator.

Alternatively or particularly preferably in combination with this, the stator comprises a laminated core which is arranged on the side of the end shield facing away from the shield plate. If the insulating body is present, this expediently encloses the laminated core. In particular, the insulating body is created by means of an encapsulation of the laminated core with plastic in this case. The laminated core has a recess, within which the fastening means is at least partially arranged. If the insulating body is present, this recess is expediently at least partially filled by means of the insulating body, wherein the insulating body is arranged in this area between the fastening means and the laminated core. By means of the laminated core on the one hand, the fastener is protected from damage, on the other hand, a relatively robust connection of the fastener is created on the stator in this way. Suitably, a bearing is attached to the stator, for example, the bearing is attached to the bearing plate, if it is present. By means of the bearing, the rotor is rotatably mounted, for which it also has a shaft connected to the bearing. The contact element has an extension, which is formed in particular on the contact portion, if it is present. By means of the extension, an outer ring of the bearing is electrically contacted. In particular, the extension is in direct mechanical contact with the outer ring of the bearing. Consequently, the potential of the outer ring is equal to ground, and prevented a static charge of the outer ring during operation of the electric machine. Conveniently, the stator comprises a central recess, within which the bearing and in particular the shaft is arranged. Conveniently, the course of the recess is parallel to the shaft. Suitably, the extension is pressed by means of the bearing against the stator. As a result, a frictional connection is created between the bearing, the extension and the stator, and thus the extension stabilized. Suitably, the extension is at least partially within the recess, if present. In particular, the extension is bent in the region of an edge of the recess and is pressed by means of the bearing against the edge. This prevents displacement of the contact element in a vibration of the electric machine.

In a suitable embodiment of the invention, the bearing consists of an electrically conductive material and expediently of a metal. In this way, the bearing is substantially completely at the same electrical potential, namely mass. However, at least the outer ring, an inner ring and at least one component in direct mechanical contact with these two rings are suitably made of an electrically conductive material so that the inner ring has the same electrical potential as the outer ring. In particular, the shaft of the rotor made of an electrically conductive material and expediently electrically contacted with the inner ring, for example, in direct mechanical contact with this. Consequently, the electrical potential of the shaft is also the same as the shield plate and thus also at least components of the rotor to ground. Consequently, a static one Charging of the rotor due to the time-varying magnetic fields excluded, for which no brushes or the like are needed.

If the bearing does not consist entirely of electrically conductive material, expediently a component of the bearing is umsp zt by means of a carbon-containing plastic. Consequently, the surface of this component is electrically conductive, and thus enables an alignment of the electrical potential of the rotor to the potential of the contact element. Alternatively, the device made of non-conductive material is surrounded by carbon fibers. In summary, the shaft of the rotor is electrically contacted by means of components of the bearing with the outer ring, wherein these components are either themselves electrically conductive or provided by means of an electrically conductive coating.

The radiator fan of the motor vehicle is in particular a main ventilator and serves to cool an internal combustion engine. Alternatively, the radiator fan is part of an air conditioning system of the motor vehicle. The radiator fan preferably comprises a fan wheel which is driven by an electric machine, which is in particular a brushless DC motor. The electric machine comprises a stator and a rotor rotatably mounted about a rotor axis, which is expediently in operative connection with the impeller. The electric machine further comprises electronics, by means of which in particular the stator is energized. Between the electronics and the stator a shield plate is arranged, which is electrically contacted with a ground terminal of a connection device of the electronics. Here, a contact element is arranged non-positively between the shield plate and the stator, which is made of an electrically conductive material. In this way, at least a portion of the stator is at an electrical potential corresponding to ground, the mounting being comparatively simple.

Embodiments of the invention will be explained in more detail with reference to a drawing. Show: 1 shows schematically a radiator fan with an electric motor,

2 perspectively the electric motor with an electronics and a

Screen plate,

3 - 5 a stator of the electric motor, with a contact element,

6 is a sectional view of the arranged between the shield plate and stator contact element in the assembled state,

7 the contact element,

Fig. 8 shows a first embodiment of a tongue, and

Fig. 9a, b, a second embodiment of the tongue plate.

Corresponding parts are provided in all figures with the same reference numerals

In Fig. 1 is a schematic simplified view in a side view of a radiator fan 2 of a motor vehicle. The radiator fan 2 comprises a radiator network 4, through which a cooling pipe 6 is guided. Within the cooling tube 6 is a cooling liquid which is kept in circulation by means of a pump, not shown here. The cooling liquid is passed through and heated by an internal combustion engine 8, wherein the internal combustion engine 8 is cooled. The heated coolant is again passed through the radiator network 4, which is acted upon by a wind. The direction of the wind is here along a wind direction 10, which corresponds substantially to the main direction of travel of the motor vehicle.

By means of a fan 12, which is arranged in the direction of air flow 10 behind the radiator network 4, the wind is amplified or generated at a standstill of the vehicle. This is done by means of an electric motor 14, which sets a fan 16 in rotation. Further, by means of the fan wheel 16, the wind is directed to the internal combustion engine 8, and this thus applied from the outside with the airstream. This leads to an additional cooling of the internal combustion engine 8. The fan 16 is disposed within a radiator frame 18, by means of which the airstream is steered. In the transition region between the frame 18 and the fan 16 are brushes or a certain contour, the each prevents a so-called leakage between the two components. The electric motor 14 is attached by means of struts 20 on the frame 18. The struts 20 are produced in one piece with the frame 18, for example in a plastic injection method.

In Fig. 2, the electric motor 14 is shown in perspective. The electric motor 14 is surrounded by a retaining ring 22 made of plastic, on which the struts 20 are formed in the form of tabs. Within the retaining ring 22 is a stator 24 of the electric motor 14, which is aligned with a shell-like shield plate 26. The opening of the shield plate 26 is oriented away from the stator 26, and the side walls of the shell-like shield plate 26 are aligned with the boundary walls of the stator 24. Within the shield plate 26, an electronics 28 is arranged. The electronics 28 include a circuit board 30 which is disposed parallel to the bottom of the shell-like shield plate 26. The printed circuit board 30 itself has a number of IBGTs and resistors and capacitors, by means of which a B6 circuit is realized. The electronics 28 further comprises a connection device 32 in the form of a plug. The connection device 32 has a ground connection 34, which is electrically contacted with the shield plate 26 (FIGS. 8, 9a, b). As a result, the shield plate 26 is in operation of the electric motor 14 to ground. In the assembled state, a corresponding plug of a wiring harness of the motor vehicle is contacted with the connection device 32, and thus makes it possible to supply the electric motor 14 with electrical energy. Furthermore, the shield plate 26 is covered with an electronics compartment lid, not shown, so that the electronics 28 is protected from damage.

Fig. 3 shows in perspective the electric motor 14 of FIG. 2, wherein the retaining ring 22 and the electronics 28 and the shield plate 26 are removed. The stator 24 has a b-side end shield 36 whose shape substantially corresponds to that of the shield plate 26. In the assembled state, the shield plate 26 is mounted on a circumferential collar 38 of the bearing plate 36. The stator 24 also has four connection contacts 40, by means of which windings, not shown, of the stator 24 are electrically contacted. The connection contacts 40 protrude by corresponding recesses of the shield plate 26 and are contacted in the assembled state with components of the circuit board 30 electrically.

The stator 24 has a central recess 42 with a round cross section. Within the recess 42, a bearing 44 is arranged, wherein an outer ring 46 of the bearing 44 is connected to the stator 42. As shown in Fig. 4, an inner ring 48 of the bearing 44 is connected to a shaft 50 of a rotor 52 shown in Fig. 5. As a result, the rotor 52 is rotatably supported about a rotor axis 54. A free end of the shaft 50 is in this case within the recess 42, whereas the remaining end of the shaft 50 is connected to the fan 16. The rotor 52 includes four circular arc-like permanent magnets 56, which are distributed around the rotor axis 54 distributed to create a ring. Here, the permanent magnets 56 are connected to a mounting shell 58, which in turn is attached to the shaft 50. The coils, not shown, which are energized by means of the connection contacts 40 are located between the permanent magnets 56 and the rotor axis 54. In other words, the electric motor 14 is an external rotor.

On the stator 24, a contact element 60 shown in perspective in FIG. 7 is fastened by means of a screw 62 arranged parallel to the rotor axis 54. The contact element 60 is made of an electrically conductive sheet metal as a stamped and bent part and comprises a C-shaped contact portion 64, at one free end of a mounting portion 66 is integrally formed. The attachment portion 66 merges into a web-like extension 68, which is angled at substantially 90 ° in comparison to the attachment portion. The mounting portion 66 has a bore 70, within which the screw 62 is arranged, wherein in the assembled state, the head of the screw 62 abuts against the mounting portion 66. The screw itself protrudes, as shown in Fig. 6 in a sectional view parallel to the rotor axis 54, through a recess 72 of the bearing plate 36, wherein the mounting portion 66 bears substantially over the entire surface of the bearing plate 36. The screw 62 is surrounded on the contact element 60 opposite side of the bearing plate 36 by means of a sleeve 74 of an insulating body 76 of the stator 24. Here, the screw 62 is rotated in a recess 77 of the insulating body 76, wherein the screw mills the associated thread during assembly. In other words, the insulating body 76 is formed in sections in the manner of a hollow cylinder, wherein the screw 72 is disposed within the hollow cylinder 74. By means of the insulating body 76, the central recess 42 of the stator 24 is further lined. The stator 24 further comprises a laminated core 78 of individual, perpendicular to the rotor axis 54 arranged and mutually insulated sheets, which has a recess 80. The recess 80 of the laminated core 78 in this case is aligned with the recess 77 of the insulating body 76 and the screw 62 is disposed with its free end within the recess 80 of the laminated core 78.

As shown in Fig. 6, in the assembled state, the contact portion 64 of the contact member 60 is frictionally between the shield plate 26 and the end shield 36 and with this in direct mechanical contact, so that the end plate 36 is at the same electrical potential as the shield plate 26. The extension 68 of the contact element 60 is disposed within the recess 42 and is pressed by means of the outer ring 44 of the bearing 42 against the insulating body 76. Here, the outer ring 44 is in direct mechanical contact with the extension 68, so that it is also grounded. Between the outer ring 44 and the inner ring 48 located, not shown balls of the bearing 44 are also made of metal or encapsulated by means of a carbon-containing plastic. Consequently, also made of metal inner ring 48 also has an electrical potential corresponding to ground. As a result, the shaft 50 that is electrically contacted with it is also grounded, and electrostatic charging of the rotor 52 is avoided.

8 shows an embodiment of the contacting of the ground terminal 34 with the shield plate 26. For this purpose, the ground terminal 34 is attached to the circuit board 30 and contacted with a sheet metal tongue 82 electrically. On the circuit board 30, a guide rail 84 is further attached, along which when mounting the Blechzu- 82 is slidable in the direction of the double arrow 86, which is parallel to the rotor axis 54.

The sheet metal tongue 82 has at its upper end a flat piece 88, which is designed here as a right angle angled end of the sheet metal tongue 82. This is in the assembled state on the guide rail 84 and goes into another, this rectangular sheet 90, so that the cross section of the metal tongue 82 is substantially U-shaped.

At the bottom, the flat piece opposite end of the metal tongue 82 is a pressure contact piece 92 in the form of a likewise bent end recognizable. There is a detent 94 which forms a rear handle to the circuit board 30. In other words, the printed circuit board 30 and the guide rail 84 are frictionally clamped between the flat piece 88 and the flat piece 94. The pressure contact piece 92 itself is pressed against the shield plate 26 by means of an attachment, not shown, of the printed circuit board 30 to the shield plate 26, so that an electrical contact between them is created.

In Fig. 9a and b, a further embodiment of the sheet metal tongue 82 is shown in perspective or perspective in a sectional view. The sheet metal tongue 82 is shortened in comparison to the embodiment shown in FIG. 8. Thus, the flat pieces 88 and 90 are missing, whereas the latching nose 94 and the pressure contact piece 92 correspond to the corresponding components shown in FIG. 8. The pressure contact piece 92 opposite end of the sheet metal tongue 82 is freiendseitig with the formation of two legs 96, 98 cut. The two legs 96, 98 are each angled at 90 °, the direction being antiparallel thereto. In other words, in a plan view of the printed circuit board 30 and on the sheet metal tongue 82, the outline of the sheet metal tongue 22 formed is substantially Z- or S-shaped.

The legs 96, 98 rest on a limiting ring 100 made of a conductive material, by means of which a border of an elongated hole 102 introduced into the printed circuit board 30 is formed. The limiting ring 100 is with Mass connected. For example, for this purpose, a strand is soldered to the limiting ring 100 or a conductor leads from the limiting ring 100 to the mass element 34th

The invention is not limited to the embodiments described above. Rather, other variants of the invention can be derived therefrom by the person skilled in the art without departing from the subject matter of the invention. In particular, all the individual features described in connection with the individual embodiments are also combinable with one another in other ways, without departing from the subject matter of the invention.

LIST OF REFERENCE NUMBERS

2 radiator fans

4 radiator network

6 cooling tube

8 internal combustion engine

10 airstream direction

12 fans

14 electric motor

16 fan wheel

18 radiator frame

20 strut

22 retaining ring

24 stator

26 screen plate

28 electronics

30 circuit board

32 connection device

34 ground connection

36 bearing plate

38 collar

40 connection contact

42 recess

44 bearings

46 outer ring

48 inner ring

50 wave

52 rotor

54 rotor axis

56 permanent magnets

58 mounting shell

60 contact element

62 screw Contact section attachment section extension

drilling

recess

extension

insulator

recess

laminated core

recess

sheet metal tongue

Guide rail Displacement direction flat piece

sheet

Pressure contact detent

leg

Limiting ring slot

Claims

claims

Electric machine (14), in particular an electric motor, of a motor vehicle, with a rotor (52) rotatably mounted about a rotor axis (54) and with a stator (24) as well as electronics (28) comprising a connection device (32), between the stator (24) and the electronics (28) having a shield plate (26) electrically contacted with a ground terminal (34) of the terminal means (32), and an electrically conductive contact member (60) between the face plate (26) and the stator is arranged frictionally.

Electric machine (14) according to claim 1,

characterized,

in that the contact element (60) has a C-shaped contact section (64).

Electric machine (14) according to claim 1 or 2,

characterized,

in that the contact element (60) is fastened to a bearing plate (36) of the stator (24) by means of a fastening means (62).

Electric machine (14) according to claim 3,

characterized,

in that the fastening means (62) is a screw or a pin, wherein a press fit is created between the pin and the stator (24).

Electric machine (14) according to claim 3 or 4,

characterized, the fastening means (62) projects through the bearing plate (36).

6. Electrical machine (14) according to claim 5,

characterized,

in that the stator (24) has an insulating body (76) which is arranged on the side of the bearing plate (36) facing away from the shield plate (26), the fastening means (62) being arranged partially within a recess (77) of the insulating body (76) is, in particular within a hollow cylindrical extension (74).

7. Electrical machine (14) according to claim 5 or 6,

characterized,

in that the stator (24) has a laminated core (78) which is arranged on the side of the bearing plate (36) facing away from the shield plate (26), wherein the fastening element (62) is arranged partially within a recess (80) of the laminated core (78) is.

8. Electrical machine (14) according to one of claims 1 to 7,

characterized,

a bearing (44) is connected to the stator (24), by means of which a shaft (50) of the rotor (52) is mounted, and in that the contact element (60) has an extension (68) by means of which an outer ring (46 ) of the bearing (44) is electrically contacted.

9. Electrical machine (14) according to claim 8,

characterized,

that the bearing (44) consists of an electrically conductive material, in particular of a metal, or that an electrically non-conductive element of the bearing (44) is encapsulated with carbon-containing plastic or surrounded by carbon fibers.

10. radiator fan (2) of a motor vehicle, in particular main fan, with an electric machine (14) according to one of claims 1 to 9.