Electric motor, in particular brushless DC motor

Abstract

The invention relates to an electric motor (1), comprising a motor support (5) having an electronics compartment (6), into which phase lines (19) connected to a stator winding (3) are guided via seals (21) to motor electronics (8), wherein: the phase lines (19) are held on a fixing element (22) with a screw opening (28); the phase lines (19) engage through plate openings (30), corresponding to connection passages (29) in the fixing element (22), of a printed circuit board (7); and the fixing element (22) is screwed to the motor carrier (5) by means of a fastening screw (23).

Description

[0001] Page 1

[0002] 2024 336 WO

[0003] Description

[0004] Electric motor, especially brushless DC motor

[0005] The invention relates to an electric motor, in particular a brushless DC motor, comprising a stator with a stator winding and a rotor, as well as a motor carrier with an electronics compartment in which motor electronics are arranged which are connected to the stator winding via phase connection contacts.

[0006] Motor vehicles often incorporate a variety of electromechanical actuators to move various components. For example, an electric or electromechanical radiator fan is used to cool an internal combustion engine or an electric motor, creating an airflow circulation. Such a radiator fan typically uses an electric motor as its drive mechanism. The electric motor can be brushed or designed as a brushless direct current (BLDC) motor, in which case it has electrical coils connected together to form a stator or rotating field winding, which are energized by (motor) electronics.

[0007] A brushless direct current (BLDC) motor, also known as an electronically commutated electric motor, is a synchronous motor that uses direct current (DC) to generate mechanical energy by rotating a rotor. Such an electric motor, as a three-phase (AC) machine, typically has a stator with a rotating field or stator winding, which is coaxially spaced across an annular gap or air gap from a rotor containing one or more permanent magnets. During operation, the stator winding generates a rotating magnetic field, which causes torque at the permanently excited rotor. Page 2

[0008] The rotor can be designed as an external rotor, which is arranged coaxially outside the stator. An external rotor typically has a rotatably mounted rotor housing (rotor bell, pole piece) as a magnetic return (rotor yoke), on the inner wall of which the permanent magnets (rotor magnets) are arranged.

[0009] In such an external rotor motor, the stationary stator is arranged radially inside the rotor, which rotates around a motor or rotor axis, so that during operation of the electric motor, the rotor rotates around the stator. If such an electric motor is advantageously used as a radiator fan drive, the external rotor is arranged in a hub housing to which radially oriented fan blades are integrally formed.

[0010] The electronic control unit (ECU) of an electronically commutated direct current (BLDC) electric motor includes a converter (inverter) that transforms direct current (DC), for example, from a vehicle's electrical system, into phase-shifted alternating currents. In the case of a three-phase electric motor, phase currents are generated that are 120° out of phase with each other and are used to power the stator or rotating field winding. The motor electronics (ECU) of such an electric motor is typically housed in an electronics compartment formed by a motor mount to which the electric motor is attached and sealed with an electronics cover that is sealed against the motor mount.

[0011] To reliably seal the motor electronics (ECU) against external environmental influences, especially moisture ingress, connecting wires leading from the motor electronics to the stator, such as wire or rod-shaped phase leads or phase connections, should be sealed. Particularly in electric motors used as fan drives (fan or radiator fan motors) in motor vehicles, high demands are placed on the sealing of the electronics compartment to protect the motor electronics, especially from moisture or contamination. Page 3

[0012] Depending on the number of phases, a BLDC motor typically requires several wires or connecting leads from the stator, which is located outside the electronics compartment, into the electronics compartment or into the interior of a corresponding ECU chamber. For the phase leads leading into the electronics compartment to connect the motor electronics to the corresponding terminals or contact points of the stator or rotating field winding, an undesirably large and expensive component (leadframe) is typically used.

[0013] When a plate-shaped component is used as the leadframe, it typically needs to be fixed to the motor mount with multiple mounting screws to generate sufficient pressure on all the necessary seals (phase seals) that seal the phase connections against the motor mount and the electronics compartment. If only a single mounting screw were used for a three-phase connection, there is a risk of uneven or asymmetrical pressure forces on the seals (phase seals). This can lead to different sealing properties or uneven sealing effects, resulting in uneven contact pressure between the phase seals and the phase leads, and thus a poorer seal quality.

[0014] The invention is based on the objective of providing a particularly suitable electric motor, especially as a fan drive for a fan module of a motor vehicle. Preferably, a reliable seal for the phase leads leading into an electronics compartment of a motor carrier should be enabled in a simple manner.

[0015] The problem is solved according to the invention by the features of claim 1. Advantageous embodiments and further developments are the subject of the dependent claims. Page 4

[0016] The electric motor is intended, in particular, for driving a motor vehicle component and is preferably a radiator fan motor for driving the impeller of a radiator fan. The electric motor is especially preferably a brushless, electronically commutated direct current (BLDC) motor. Further preferably, the electric motor is an external rotor motor, wherein the rotor surrounds the stator and has a pot-shaped rotor housing with permanent magnets arranged on the inner walls.

[0017] The electric motor comprises a stator with a stator or rotating field winding and a rotor, as well as a motor carrier with an electronics compartment housing motor electronics. Phase leads or phase connection leads, connected to or contactable with the stator or rotating field winding, are guided into this compartment via through-holes provided in the motor carrier. Seals, preferably elastomer or rubber seals, are inserted into these carrier-side through-holes, enclosing the phase leads like a sealing sleeve. Motor electronics

[0018] The phase leads, preferably with already attached (phase) seals, are held by a fixing element with a central screw opening. The terminals of the phase leads, corresponding to the motor electronics, pass through connection openings in the fixing element. These connection openings correspond to or align with the openings in the motor electronics or its circuit board. The fixing element is screwed to the motor mount by means of a fastening screw that passes through its central screw opening, particularly under uniform pressure on the seals. Preferably, only a single fastening screw is provided, with which the fixing element, along with the phase leads and the attached (phase) seals, is screwed to the motor mount.

[0019] In an advantageous embodiment, the fixing element has a triangular base plate or a corresponding triangular base body with three corner areas for a three-phase stator or rotating field winding. (See page 5.)

[0020] In the corner areas, sockets, also referred to as receiving sleeves, are provided with connection openings for the corresponding terminals of the phase leads. In other words, the fixing element has hollow cylindrical sockets into which the phase leads are inserted with their electronic terminals. The fixing element is preferably a small plastic component.

[0021] When a fastening screw is located in the central screw hole of the fixing element, its longitudinal axis defines the screw axis. The connection feedthroughs are radially offset from the central screw hole relative to this screw axis. The radial spacing of the connection feedthroughs, and thus the radial spacing of the individual phase conductors from the center of the screw hole of the fixing element, can be the same or different.

[0022] A particularly advantageous design of the fixing element provides that it has a support leg, also referred to below as a compensating extension. This is suitably a structural element for compensating extension in order to achieve a uniform and efficient seal of all seals (phase seals) with only a single fastening screw. The support leg, or the compensating extension, which is particularly finger-like, extends radially with respect to the screw axis of the fastening screw that passes through the central screw hole.

[0023] Preferably, the support leg or compensating arm extends radially opposite the phase line or connection bushing that has a smaller radial spacing compared to the other connection bushings or phase lines. The support leg or compensating arm is suitably integrally formed on a longitudinal side of the fixing element or its base plate or body. Page 6

[0024] The support leg or compensating arm suitably acts as a counter-compensating extension, bending or deforming the seal or the phase line supporting it in such a way that the sealing pressure generated by the individual fastening screw is distributed evenly across all seals (phase seals). In other words, the fixing element equalizes the pressure or pressing force on all phase seals. This pressure force equalization is advantageously achieved by means of the support leg or compensating arm, particularly due to differential deformation of the fixing element and / or the seals.

[0025] According to a suitable further development, the fixing element has a number of, preferably two, joining pins which engage in corresponding joining openings in the printed circuit board. This enables additional centering or positioning, in particular preventing rotation, of the fixing element relative to the printed circuit board of the motor electronics. Additionally or alternatively, a recess adapted to the outer contour of the fixing element is provided in the motor carrier within the electronics compartment, in which the fixing element is securely positioned.

[0026] In a suitable embodiment, the seals are conical or wedge-shaped in longitudinal section, with a sealing tip that extends into the corresponding through-opening of the motor mount. Advantageously, the seals have a number of circumferential sealing ribs on their outer circumference, particularly forming a labyrinth seal.

[0027] The advantages achieved with the invention lie particularly in the fact that the electronics compartment of the motor mount can be sealed using simple (elastomeric or rubber) seals and a single fastening screw, thanks to the fixing element that carries the phase leads. This makes it possible to compress all seals (phase seals) evenly using only one fastening screw, thus achieving a reliable and cost-effective seal. Furthermore, it enables a simple and reliable insertion and assembly process for the phase leads.

[0028] An embodiment of the invention is explained in more detail below with reference to a drawing. The drawing shows:

[0029] Fig. 1 shows a sectional view of an electric motor with a motor carrier with motor electronics arranged in an electronics compartment, the phase lines of which are joined with a fixing element and sealed against the motor carrier.

[0030] Fig. 2 shows a perspective view of the motor carrier with the motor electronics circuit board located in the electronics compartment.

[0031] Fig. 3 shows an exploded view of the motor carrier and the circuit board with phase leads inserted therein, looking into the electronics compartment at the through-holes of the motor carrier and the seals associated with them.

[0032] Fig. 4 shows an exploded view of the circuit board and the fixing element with the phase leads arranged on it, as well as the seals associated with them, and

[0033] Fig. 5 shows a perspective rear or bottom view of the circuit board with the fixing element attached to it, with the phase lines and the seals surrounding them.

[0034] Corresponding parts are marked with the same reference symbols in all figures.

[0035] Figure 1 shows an electric motor 1, which is designed as a brushless DC motor (BLDC) with an external rotor. The electric motor 1 has a stator 2 designed as a laminated core with a number of stator teeth (not specified) which are wound with a three-phase rotating field winding (stator winding) 3. The electric motor 1 also has a rotor 4 and a motor mount 5. Page 8

[0036] With reference to Figure 2, the motor mount 5 has an electronics compartment 6 in which a circuit board 7 of a motor electronics unit 8, populated with unspecified electronic components, is located. The electronics compartment 6 is closed and sealed with an electronics cover 9. The motor mount 5 is designed for mounting and securing the electric motor 1 at a desired installation location, preferably as a mechanical mounting interface to a vehicle part, for example, a radiator fan drive on a fan shroud. For this purpose, the motor mount 5 has, for example, circumferentially projecting screw or flange tabs 10.

[0037] The rotor 4 is rotatably mounted on a stationary rotor shaft 11, which forms the axis of rotation for the rotor 4's rotational movement. The rotor shaft 11 is positively and non-positively engaged, and in particular rotationally fixed, in a support bushing 12 of the motor carrier 5. The rotor 4 has a cup-shaped rotor housing 13, which is, for example, a deep-drawn part made of sheet steel. The rotor housing 13 has a housing base 14 and a hollow cylindrical housing wall 15. Arc-shaped permanent magnets 16 of a magnet arrangement are bonded to the inner wall or inner surface of the tubular or hollow cylindrical housing wall 15. A bearing seat 17 for receiving two axially spaced rolling bearings 18 is provided in the housing base 14, by means of which the rotor 4 is rotatably mounted on the rotor shaft 11.The rotor 4 is, for example, non-rotatably coupled to a fan hub of a fan wheel by means of the rotor housing 13, in particular via the housing base 14, for example by being screwed to it.

[0038] The motor electronics 8 are connected to the rotating field winding 3 of the stator 2 via phase lines 19. In the three-phase electric motor 1 of the exemplary embodiment, the three phase lines 19 are routed through the stator 2 to near the bottom of the housing 14. A rotating field or stator-side connection end 19a of each phase line 19 is electrically connected to a corresponding phase contact 20 of the rotating field winding 3. Page 9

[0039] The respective phase conductor 19 is guided through a seal 21 and connected to a fixing element 22 at a terminal end 19b associated with the motor electronics 8. This fixing element 22 is screwed to the motor carrier 5 by means of a single fastening screw 23. The seal 21 of the respective phase conductor 19 sits in a preferably conical or tapered through-opening 24 of the motor carrier 5 within the electronics compartment 6, in particular with a sealing effect or pressure or pressing force as intended by means of the fixing element 22 and the single fastening screw 23. The respective seal 21 is conical or wedge-shaped in longitudinal section with a sealing tip that extends into the corresponding through-opening 24 of the motor carrier 5. The seals 21 have a number of circumferential sealing ribs 21a on their outer circumference.

[0040] Figure 2 shows a top view of the motor mount 5 without the electronics cover 9, looking into the electronics compartment 6 at the motor electronics 8 and its populated circuit board 7. The motor electronics 8 are electrically connected via a terminal or plug contact 25, through which a DC voltage, in particular from a vehicle electrical system, is supplied, so that the motor electronics 8 are supplied with a direct current (DC). During operation of the electric motor 1, this is converted by means of an inverter, in particular a bridge circuit with semiconductor switches preferably connected in a bridge configuration, into three phase-shifted phase currents, which are used to energize the rotating field winding 3 of the stator 2 via the phase lines 19.

[0041] Figure 2 shows that the fastening screw 23, with its screw head 23a, completely passes through a (plate-side) through-hole 26 of the circuit board 7 in the area of ​​the fixing element 22, which is not visible here and is located on the back of the circuit board 7. Thus, the single fastening screw 23, accessible via the electronics compartment 6, only fastens the fixing element 22 to the motor mount 5. Figure 2 illustrates the screw or rotation axis 27 of the fastening screw 23. Page 10

[0042] Figures 3, 4, and 5 show, in different views, the circuit board 7 and the fixing element 22, as well as the phase leads 19 and seals 21 associated with or arranged on it. The phase leads 19 are held on the fixing element 22, preferably with the (phase) seals 21 already attached. The fixing element 22 has a central screw opening 28. The screw or rotation axis 27 of the fastening screw 23 runs centrally in and perpendicular to this screw opening 28. The fixing element 22 has connection openings 29 through which the circuit board or electronics-side connection ends 19b of the phase leads 19 extend. Corresponding plate openings 30 of the circuit board 7 are aligned with these connection openings 29 of the fixing element 22.In the assembly state of the phase leads 19 with the fixing element 22 and with the circuit board 7, the plate- or electronic-side connection ends 19b of the phase leads 19 penetrate the connection feedthroughs 29 and the plate openings 30 in order to contact the phase leads 19 with the motor electronics 8, for example by soldering them to corresponding conductor tracks of the circuit board 7.

[0043] During the assembly of the fixing element 22 by means of the fastening screw 23, this screw passes through the plate-side through-opening 26 of the circuit board 7 and the central screw opening 28. This allows the fixing element 22 with the phase leads 19 and the (phase) seals 21 attached to them to be screwed to the motor carrier 5 under uniform pressure on the seals 21.

[0044] The fixing element 22 has a triangular base plate 22a or a corresponding triangular body with three corner regions 22b for the three-phase stator or rotating field winding 3. Due to this shape or geometry, the fixing element 22 has a small footprint. Receptacles or sockets 22c with connecting passages 29 are provided in the corner regions 22b of the fixing element 22. The associated connecting ends 19b of the phase conductors 19 are inserted into these sockets or sockets. The fixing element 22 is made of an electrically insulating material, preferably a plastic. Page 11

[0045] With respect to the screw axis 27 of the fastening screw 23, the receiving or plug-in sockets 22c, and thus the connection feedthroughs 29, are radially offset from the central screw opening 27. The radial spacing of the connection feedthroughs 29, and thus the radial spacing of the individual phase conductors 19 to the screw axis 27 or to the center of the central screw opening 28 of the fixing element 22, is the same for the two outer connection feedthroughs 29. In contrast, the middle connection feedthrough 29 has a comparatively small radial spacing.

[0046] Opposite the central connection opening 29, the fixing element 22 has a finger-shaped support leg 31 designed as a compensating extension. This is a structural element for compensating extension, so that a uniform and efficient seal of all seals (phase seals) 21 with the single fastening screw 23 is achieved. The support leg 31 extends radially in the manner of a cantilever and with respect to the screw axis 27 of the fastening screw 23.

[0047] In other words, the support leg 31 extends radially opposite the connection bushing 29 and the phase conductor 19 inserted therein, which has a smaller radial distance compared to the other connection bushings 29 and the phase conductors 19 inserted therein. The support leg 31, as a compensating arm, is therefore integrally formed on the longitudinal side 22d of the fixing element 22 or its base plate or body 22a.

[0048] In the exemplary embodiment, the fixing element 22 has two joining pins 22e which engage in corresponding joining openings 7a of the circuit board 7. This achieves advantageous centering, positioning, and / or rotational locking of the fixing element 22 relative to the circuit board 7. Additionally or alternatively, a recess 32 adapted to the outer contour of the fixing element 22 is formed in the motor carrier 5 within the electronics compartment 6, in which the fixing element 22 is inserted. Page 12

[0049] Figure 5 shows the motor carrier 5 with a view into the electronics compartment 6 and the motor electronics 8 with the circuit board 7, as well as the phase leads 19 and the seals 21 connected to it, in a pre-assembled position. The phase leads 19, together with the fixing element 22 (not visible here), are attached to the circuit board 7 of the motor electronics 8, so that it can be inserted into the electronics compartment 6. The phase leads 19, together with their seals 21, extend through the corresponding through-openings 24 on the carrier side, into which the seals 21 are already inserted or will be inserted together with the phase leads 19.

[0050] In the assembled state, with the phase connections 19 contacted with the rotating field winding 3 of the stator 2, the motor electronics 8 housed in the electronics compartment 6 and the plug or connection contact 25 are each screwed to the motor carrier 5 by a screw 33 or 34, respectively. The electronics compartment 6 of the motor carrier 5 is sealed by means of the seals 21 with the fixing element 22, which carries the phase leads 19. All seals (phase seals) 21 are uniformly compressed by means of the single fastening screw 23. This ensures a reliable and cost-effective seal while simultaneously enabling a simple and error-free assembly process for the phase leads 19.

[0051] In summary, the invention relates to an electric motor 1 with a motor carrier 5 with an electronics compartment 6, into which phase lines 19 connected to a stator winding 3 are led via seals 21 to a motor electronics 8, wherein the phase lines 19 are held on a fixing element 22, wherein the phase lines 19 with connection feedthroughs 29 of the fixing element 22 pass through plate openings 30 of a circuit board 7 of the motor electronics 8 corresponding to plate openings 30, and wherein the fixing element 22 is screwed to the motor carrier 5 by means of a fastening screw 23.

[0052] The claimed invention is not limited to the embodiments described above. Rather, other variants of the invention (page 13) can also be derived by a person skilled in the art within the scope of the disclosed claims without departing from the subject matter of the claimed invention. In particular, all individual features described in connection with the various embodiments can also be combined in other ways within the scope of the disclosed claims without departing from the subject matter of the claimed invention.

[0053] Page 14

[0054] Reference symbol list

[0055] 1 electric motor

[0056] 2 Stator

[0057] 3 Rotating field / stator winding

[0058] 4 Rotor

[0059] 5 engine mounts

[0060] 6 Electronic compartment

[0061] 7 printed circuit board

[0062] 7a Joining opening

[0063] 8 Motor electronics

[0064] 9 Electronic covers

[0065] 10 screw / flange straps

[0066] 11 Rotor axis

[0067] 12 Carrier socket

[0068] 13 Rotor housings

[0069] 14 Case base

[0070] 15 Housing wall

[0071] 16 permanent magnet

[0072] 17 bearing seat

[0073] 18 rolling bearings

[0074] 19 Phase line

[0075] 19a stator-side

[0076] 19b Electronic-side connection end

[0077] 20 phase contacts

[0078] 21 Phase / Seal

[0079] 21a Sealing rib

[0080] 22 Fixing element

[0081] 22a Base plate body

[0082] 22b Corner area

[0083] 22c socket / receptacle

[0084] 22d Long side

[0085] 22e Joining pin Page 15

[0086] 23 Fastening screw

[0087] 23a Screw head

[0088] 24 carrier-side through opening

[0089] 25 Connection / plug contact 26 Plate-side through-hole

[0090] 27 Screw / rotary axis

[0091] 28 screw opening

[0092] 29 Connection feedthrough

[0093] 30 Plate opening 31 Support leg / compensating cantilever

[0094] 32 Exclusion

[0095] 33 screw

[0096] 34 screw

Claims

Page 16 Claims 1. Electric motor (1) for driving a motor vehicle component, in particular a radiator fan motor, comprising a stator (2) with a stator or rotating field winding (3) and a rotor (4) as well as a motor carrier (5) with an electronics compartment (6) accommodating motor electronics (8), into which phase lines (19) connected or contactable with the stator or rotating field winding (3) are guided via seals (21) inserted in through-openings (24) of the motor carrier (5), - wherein the phase lines (19) are connected to the seals surrounding them (21) are held on a fixing element (22) with a central screw opening (28), - wherein the terminal ends (19b) of the phase lines (19) assigned to the motor electronics (8) are connected to the terminal feedthroughs (29) of the fixing element (22) reach through corresponding plate openings (30) of a printed circuit board (7) of the motor electronics (8), and - wherein the fixing element (22) is screwed to the motor carrier (5) by means of a fastening screw (23) passing through its central screw opening (28), in particular under uniform pressure on the seals (21).

2. Electric motor (1 ) according to claim 1 , characterized in that the fixing element (22) has a support leg or support finger (31), in particular as or in the manner of a compensating arm, which extends radially with respect to the screw axis (27) of the fastening screw (23) passing through the central screw opening (28).

3. Electric motor (1) according to claim 1 or 2, characterized in that the fixing element (22) has a triangular base plate (22a) in the corner regions (22b) of which the connection passages (29) are arranged. Page 17 4. Electric motor (1) according to claim 3, characterized in that the support leg (31) is formed on a longitudinal side (22d) of the fixing element (22) or its base plate (22a).

5. Electric motor (1) according to one of claims 1 to 4, characterized in that the connection feedthroughs (29) are provided in receiving sockets (22c) of the fixing element (22), wherein the phase lines (19) are inserted at their ends into the receiving sockets (22c).

6. Electric motor (1) according to one of claims 1 to 5, characterized in that the connection feedthroughs (29) are arranged radially offset to the central screw opening (28) with respect to the screw axis (27) of the fastening screw (23).

7. Electric motor (1) according to one of claims 1 to 6, characterized in that the fixing element (22) has a number of, preferably two, joining pins (22e) which engage in corresponding joining openings (7a) of the circuit board (7).

8. Electric motor (5) according to one of claims 1 to 7, characterized in that the seals (21) are conical or wedge-shaped in longitudinal section.

9. Electric motor (1) according to one of claims 1 to 8, characterized in that the seals (21) have a number of circumferential sealing ribs (21a) on the outer circumference. Page 18 10. Electric motor (1) according to one of claims 1 to 9, characterized in that the rotor (4) as an external rotor surrounds the stator (2) and has a pot-shaped rotor housing (13) with permanent magnets (16) arranged on the inner wall.

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