Electronically commutated electric motor with liquid cooling

Abstract

The present invention relates to an electronically commutated electric motor comprising a liquid-cooled stator with an ironless hollow-cylindrical stator winding and a coolant circuit for conducting a coolant through the electric motor, a rotor arranged rotatably concentrically to the stator, a motor housing accommodating the stator and the rotor, a connection assembly and at least one electrical connection line for electrically connecting the stator winding. The invention also relates to a connection assembly for such an electronically commutated electric motor. The connection assembly has a closure cover, at least one plug-in connection means for establishing electrical contact between the stator winding and the electrical connection line, and also a sealing element between the plug-in connection means and a housing of the connection assembly, wherein the connection assembly implements fluid-tight sealing of the motor housing.

Description

[0001] ELECTRONICALLY COMMUTATED LIQUID-COOLED ELECTRIC MOTOR

[0002] The present invention relates to an electronically commutated electric motor comprising a liquid-cooled stator with an ironless hollow cylindrical stator winding and a coolant circuit for conducting a coolant through the electric motor, a rotor arranged concentrically to the stator for rotation, a motor housing accommodating the stator and the rotor, a termination assembly, and at least one electrical connection cable for electrically connecting the stator winding. Furthermore, the invention relates to a connection assembly for such an electronically commutated electric motor.

[0003] Electric motors with a liquid-cooled stator are well-known in technology and are used in various applications where adequate cooling of the waste heat generated by the electric motor's power loss is not guaranteed. Such liquid-cooled electric motors are used in aviation, automotive engineering, and air conditioning technology, as well as in space travel, raw material extraction, and power plant technology.

[0004] A generic liquid-cooled electric motor is known, for example, from US 6489 697 B1. This electric motor has a hollow cylindrical stator winding enclosed by a soft magnetic yoke, and a rotor arranged to rotate concentrically to the stator. The stator winding with yoke and the rotor are housed in a motor housing provided with a cover plate on both sides. An oil circuit is provided to dissipate the heat loss generated at the stator winding and yoke, with the cooling medium flowing axially, first along the inner circumference of the stator winding and then along the outer circumference of the yoke. A ceramic sleeve is provided between the stator winding and the rotor, defining both the running gap to the rotor and the hollow cylindrical flow channel for the coolant between the ceramic sleeve and the stator winding.However, this liquid-cooled electric motor is relatively complex in its design, making it both costly to produce and prone to failure during operation. Due to its active cooling system, this electric motor requires regular maintenance.

[0005] In addition, there are electric motors that are hermetically sealed for use in extreme environmental conditions. The areas of application for such hermetically sealed electric motors range from automotive engineering to medical technology. DE 38 04 677 A1, for example, describes such an electric motor with a watertight seal for the conductor feedthrough between the housing front edge and an end cover, wherein a contact pin provided outside the housing for the plug-in contact is connected to an electrical connection cable via a circuit board in the end cover and cable wires to a stator winding. The document US 10 389 202 B2 also shows a hermetically sealed electric motor in which contact pins protruding outside the motor housing are connected to the stator windings via a circuit board embedded in the end cover.In addition to the contact pins and circuit boards, the motor control unit is also embedded in the cover of the motor housing. The latter two documents do not depict an electric motor with a coolant flowing through the motor.

[0006] It is the object of the present invention to improve an electronically commutated electric motor of the type mentioned at the outset with regard to ease of assembly, trouble-free operation and simple construction.

[0007] This object is achieved in that the connection assembly comprises a cover plate and at least one plug-in connection means for electrically contacting the electrical connection line with a corresponding plug-in connection part of the stator winding of the stator, and in that the connection assembly effects a fluid-tight seal of the motor housing, wherein a sealing element is provided between the plug-in connection means and a housing of the connection assembly. This connection of a stator winding of such a hollow-cylindrical stator with a preferably slotless stator winding enables sealing of the motor housing against liquid leakage, in particular against a coolant of a coolant circuit.In addition, the fluid-tight connection of the connection assembly to the motor housing prevents substances surrounding the electric motor, such as liquids or gases, from reaching the electrical contact of the motor housing or entering the motor housing and thus damaging the electric motor. Furthermore, the simple electrical connection of the stator winding to the electrical connection cable is enabled using an electrical plug connection. The connection assembly, designed as an end cover to close off an open front side of the motor housing, is a separate component that is provided during assembly of the electric motor and is firmly connected to the motor housing, for example by means of a screw connection or a clip connection. In one variant, the connection assembly can also be designed to be removable and replaceable if necessary.In an electric motor according to the invention, the electrical connection of the stator winding to the electrical connecting cable is established within the connection assembly or within the motor housing, which is sealed from the environment by the connection assembly. The electrical connection between the plug-in connector and the electrical connecting cable leading into the connection assembly is also implemented within the connection assembly. The electrical contact between the electrical connecting cable and the stator winding is established in the connection assembly by the plug-in connector, which is connected to the electrical connecting cable, and the plug-in connector part, which is connected to the stator winding.

[0008] The stator winding is preferably formed by several individual coils, particularly preferably by twelve individual coils. The individual coils are preferably connected by means of a star or delta connection to form a three-phase winding system with three stator winding phases. Each winding phase preferably consists of four individual coils.

[0009] In a particularly preferred embodiment, the stator has a stator winding with three stator winding phases and three plug-in connectors, each connected to a stator winding phase, which are positioned on the first side of the motor housing. The connection assembly has three plug-in connectors, each connected to an electrical connecting line. The individual stator winding phases are preferably formed by several individual coils, particularly preferably by four individual coils. The individual coils are preferably connected to a three-phase winding system using a star or delta connection. A three-phase winding system enables the rotor to be started or stopped from or in any desired holding position, while at the same time the wiring effort for three phases is relatively low.

[0010] In an advantageous embodiment, the rotor comprises at least one permanent magnet or several permanent magnet segments distributed around the circumference. The rotor is preferably designed with two, four, or six poles. Advantageously, permanent magnets distributed around the circumference are arranged in a Halbach arrangement, with several permanent magnet segments, in particular two permanent magnet segments, forming a magnetic pole. A multi-pole pair design of the permanent magnet arrangement allows for a particularly high torque to be generated.

[0011] In a preferred embodiment of mounting the connection assembly to the motor housing, the plug-in connector, which is connected to an electrical connection cable, is connected to a corresponding plug-in connector part of the stator winding by sliding it onto it, and the connection assembly is secured to the motor housing. In addition to the very simple assembly, different connection assemblies can also be used without replacing or adapting the stator and the rotor, which is arranged rotatably within the inner circumference of the stator.

[0012] In a simple variant, the connector of the connection module can be designed as a socket, and the corresponding connector part of the stator winding can preferably be designed as a contact pin. Such a socket enables a simple, detachable plug connection for electrically contacting the electrical connection cable with the stator winding. A connector part complementary to the socket, for example, a contact pin, is connected directly to the stator winding of the stator, thus enabling the stator winding to be supplied with power via a simple plug connection between the connection module and the motor housing.

[0013] Conveniently, an O-ring can be provided as a sealing element between the socket and a housing of the connector assembly. For very high requirements regarding the tightness of the connector assembly with respect to the electrical connection cable, an O-ring can be arranged in a gap between the socket and the housing of the connector assembly, in addition to the inherent sealing effect of the electrical connection cable embedded in the connector assembly and the embedded socket.

[0014] A practical embodiment provides for a radial seal between the connection assembly and the motor housing. The radial seal enables secure sealing of the interface between the motor housing and the connection assembly, so that high sealing requirements can be met both from the outside in and from the inside out. Optionally, in addition to the radial seal, a supplementary axial seal, such as a flange seal, can be provided between the connection assembly and the motor housing to improve the tightness against leakage of coolant from the cooling circuit and the durability of the seal between the connection assembly and the motor housing.

[0015] A further embodiment provides for a cable assembly, wherein the cable assembly has the electrical connecting cable, the plug-in connection means and at least one busbar for the electrical connection of the electrical connecting cable to the plug-in connection means. Such a prefabricated cable assembly enables easier production of the connection assembly, in particular during injection molding or molding of the connection assembly, as well as good sealing of the electrical connection between the electrical connecting cable or the busbar and the housing of the connection assembly. The connection between the busbar and the plug-in connection means is preferably made by pressing, welding or soldering. On the other hand, the electrical connecting cable is connected to the busbar, in particular by welding or soldering.Depending on the number of stator winding phases, the cable assembly can comprise several electrical connecting cables, busbars, and plug-in connectors, which are combined into a single cable assembly for time-saving further processing. During the manufacturing process of the connection assembly, the cable assembly is held in a defined position in a mold so that during the subsequent assembly of the connection assembly on the open end face or on the first side of the motor housing, the position of the plug-in connectors precisely matches the position of the plug-in connectors positioned on the motor housing and connected to the stator winding phases.

[0016] Preferably, the cable assembly can comprise three electrical connection cables, three sockets, and three busbars, wherein the three electrical connection cables, the three sockets, and the three busbars are mechanically connected to one another. Combining several connection components into a common cable assembly enables easy handling of the common cable assembly during production of the connection assembly.

[0017] A practical design involves manufacturing the connection assembly from a thermoplastic or thermosetting plastic by injection molding or encapsulation, with the connection electronics including the electrical connection cable and the plug-in connector embedded in the connection assembly. The connection electronics enables simple electrical connection of the individual stator winding phases to a power supply, with this electrical interface being molded or encapsulated in the connection assembly. The connection electronics can be implemented in the form of a populated printed circuit board with all the necessary components and connecting cables.

[0018] A further modification provides for commutation electronics to be provided for commutation of the electric motor, wherein the commutation electronics are also embedded in the connection module. This eliminates the need for separate provision and arrangement of the commutation electronics on the motor housing. The commutation electronics are designed, in particular, as a printed circuit board with all necessary components, electronic components, and cables and can optionally be combined with the connection electronics. Furthermore, the commutation electronics can also have an integrated sensor, preferably a magnetic field-sensitive angular position sensor, which in particular detects the magnetic field of a diametrical control magnet mounted at the end of a rotor shaft. Such an integrated position sensor enables simple control of an electronically commutated electric motor.

[0019] A special embodiment provides for the connection electronics and / or the commutation electronics to be provided with an additional layer of a thermoplastic or thermosetting plastic, which is applied in a prior first step by injection molding, transfer molding, or mold encapsulation. This means that the sensitive electrical and electronic components are doubly overmolded and / or encapsulated in a two-stage process and thus offer special protection. Therefore, in a first process step during the manufacture of the connection module, the connection electronics and / or the commutation electronics, including all circuit boards, components, and cables, are overmolded on all sides with a defined material thickness of a preferably thermoplastic plastic.To ensure hermetic sealing, these already encapsulated components are embedded once again in a thermoplastic or thermosetting plastic in the second process step, thereby securely sealing any possible retaining positions from the first process step. In addition to sealing the components, this second process step also forms the housing shape of the connection assembly with an integrated end cover.

[0020] An advantageous embodiment provides that the coolant circuit for passing a coolant through the electric motor further comprises a first coolant channel between the motor housing and the outer circumference of the stator, a second coolant channel between the inner circumference of the stator and the rotor, and a coolant deflector for fluidly connecting the first coolant channel and the second coolant channel, wherein the coolant deflector is preferably formed, at least partially, by the connection assembly. In an electric motor according to the invention, oil or a special heat transfer fluid, preferably with a boiling point above 200°C, is used as the coolant. By passing such a coolant through the coolant circuit, effective cooling of the electric motor is achieved.The coolant absorbs the magnetic reversal and eddy current losses of the return material at the gap between the outer wall of the motor housing and the outer circumference of the stator. As the coolant flows through the running gap between the inner circumference of the stator and the rotor, the ohmic losses and eddy current losses in the stator winding are dissipated. This ensures that the two heat-dissipating components, the stator winding and return, are in direct contact with the coolant, thus enabling optimal heat dissipation. The coolant circuit preferably allows a flow rate of 2 to 7 liters per minute. The coolant is forced through the coolant circuit at a pressure of between 1 and 10 bar, preferably between 3 and 5 bar. The coolant can dissipate a thermal power loss of the electric motor of 3 kW, 5 kW or more.

[0021] A sensible design provides for the second coolant channel between the inner circumference of the stator and the rotor to have a smaller cross-sectional area than the first coolant channel between the motor housing and the outer circumference of the stator. Since, under high loads on the electric motor, the majority of the power loss and thus the heat generation occurs in the stator winding, the narrower cross-section in the running gap between the stator winding and the rotor enables better heat transfer and lower thermal load on the electric motor via turbulent coolant flow. Furthermore, with a large air gap between the stator and rotor, high torque cannot be generated, or a small air gap is necessary to generate high torque.

[0022] In a modification of the connection assembly, the coolant diversion can be designed as a bore or opening in the connection assembly. This enables targeted redirection of the coolant in the coolant circuit and prevents stagnation zones and deposits in the coolant circuit. Accordingly, a coolant diversion formed in the connection assembly for fluidly connecting the first and second coolant channels can contribute to improved heat transfer.

[0023] A practical variant provides for the coolant circuit to have a coolant inlet to the first coolant channel arranged on the circumference of the motor housing and preferably a coolant outlet from the second coolant channel, wherein the coolant outlet is arranged on a second side of the motor housing opposite the connection assembly. Via the coolant inlet on the motor housing, which can be designed, for example, as bores distributed around the circumference, the coolant flows directly into the gap between the motor housing and the outer circumference of the stator and then via the coolant deflector and the second coolant channel to the outlet provided on the second side of the motor housing, which in turn can be designed as bores. This also allows the output-side ball bearing of the motor shaft to be cooled and supplied with lubricant by the oil used as coolant.In an alternative design, the coolant inlet and coolant outlet can also be reversed, so that the coolant inlet is located on the second side of the motor housing and the coolant outlet is located on the periphery of the motor housing. In this design, the coolant flows from the alternative coolant inlet on the second side of the motor housing, first through the second coolant channel, and then via the coolant diverter through the first coolant channel to the alternative coolant outlet on the periphery of the motor housing.

[0024] A further advantageous embodiment provides that the connection assembly effects a fluid-tight seal between the electrical contact of the plug connection means of the electrical connection cable with the corresponding plug connection part of the stator winding of the stator and the coolant circuit of the electric motor.

[0025] Furthermore, the invention relates to a connection assembly for an electronically commutated electric motor according to one of the previously described embodiments, wherein the connection assembly comprises an end cover of the electronically commutated electric motor and at least one electrical connecting cable, at least one plug-in connection means for electrically contacting the stator winding with the electrical connecting cable, and a sealing element between the plug-in connection means and a housing of the connection assembly. This connection assembly, in conjunction with the motor housing of the electric motor, enables a fluid-tight seal on the corresponding side of the motor housing and electrical contacting of the stator winding by means of the plug-in connection means. Thus, in addition to an interface sealed against fluid exchange, the connection assembly also forms an electrical interface for the power supply of the electric motor.

[0026] In a particularly preferred application, the electronically commutated electric motor with liquid-cooled stator can be used in raw material extraction, particularly in oil and gas extraction.

[0027] A non-limiting embodiment of the invention is explained in more detail below with reference to exemplary drawings. They show:

[0028] Fig. 1 is a partially cutaway side view of an electronically commutated electric motor according to the invention,

[0029] Fig. 2 is a sectional view through the electric motor from Fig. 1, Fig. 3 is a perspective exploded view of the electric motor from Fig. 1,

[0030] Fig. 4 is a partially cutaway, enlarged view of the connection assembly of the electric motor from Fig. 1, and

[0031] Fig. 5 is a perspective view of a pre-assembled cable assembly for a connection assembly of the electric motor according to the invention from Fig. 1.

[0032] The electronically commutated electric motor 1 according to the invention shown in Figs. 1 and 2 is designed as an internal rotor and is liquid-cooled. The electric motor 1 comprises a rotor 2, which is aligned concentrically with a hollow cylindrical stator 3 and rotatably arranged in the stator 3. The rotor 2 is not shown in section in both the partially cutaway side view of the electric motor 1 in Fig. 1 and the corresponding sectional view in Fig. 2. The rotor 2 comprises at least one permanent magnet or several permanent magnet segments distributed over the circumference. In a cylindrical motor housing 4, preferably made of steel, all other components of the electric motor 1 according to the invention can be accommodated or arranged in addition to the stator 3 and the rotor 2. The first side of the motor housing 4 is sealed in a fluid-tight manner with a connection assembly 5. The connection assembly 5 serves to electrically contact the electric motor 1.The essentially hermetic sealing of the motor housing 4 by the connection assembly 5 prevents both the leakage of coolant from the interior of the electric motor 1 and the penetration of unwanted media into the electric motor 1. The second side or output side of the motor housing 4 is located opposite the connection assembly 5. The motor housing 4 can be cup-shaped and constructed in one piece, with the bottom of the cup representing the second side of the motor housing and the open end of the cup representing the first side of the motor housing. The first open end of the motor housing 4 can be sealed fluid-tight with the connection assembly 5.A one-piece motor housing 4 consisting of a cylindrical motor housing and the second side of the motor housing has the advantage that there is no transitional connection between the two parts through which cooling fluid could escape from the interior of the electric motor 1 or through which undesirable media could penetrate the electric motor 1. A one-piece motor housing 4 can also be manufactured more cost-effectively, since the cylindrical part of the motor housing does not need to be fluid-tightly connected to the second side of the motor housing in an additional work step. The liquid-cooled stator 3 of the electric motor 1 according to the invention consists of an ironless, hollow-cylindrical, self-supporting stator winding 6, which is divided into several individual coils, and an externally arranged soft magnetic return path 7.The external short circuit 7 consists of a laminated core, is also hollow-cylindrical in design, and encloses the stator winding 6, with the short circuit 7 being in positive contact with the stator winding 6. The hollow-cylindrical stator winding 6 can be wound from a baked enamel wire which is heated during production and, when cured, holds the stator winding 6 together in a dimensionally stable manner at low temperatures. Furthermore, a hollow-cylindrical ceramic support sleeve can be provided which, for use at high temperatures, is arranged inside and concentrically to the stator winding 6. Such a ceramic support sleeve ensures the required air gap between the rotor 2 and stator 3 even at high operating temperatures. The stator winding 6 can also be coated with a potting compound which increases the stability of the stator winding 6, particularly at high operating temperatures, and completely encapsulates the stator winding 6.

[0033] A rotor shaft 8, which extends coaxially through the rotor 2 or is attached to the rotor 2 as a shaft stub, is supported both in a rolling bearing 9 arranged on the second side of the motor housing 4 and in an opposite second rolling bearing 10, which is accommodated in a front-end flange 25 in the region of the first side of the motor housing. The part of the rotor shaft protruding from the motor housing 4 can have connecting gearing.

[0034] The electronically commutated electric motor 1 according to the invention further comprises a coolant circuit 12, with a coolant inlet 13, which is formed from a plurality of bores provided on the circumference of the motor housing 4 and arranged in a circumferential recess opposite the motor housing 4, a first coolant channel 14, which runs in a ring shape between the motor housing 4 and the outer circumference of the stator, a coolant deflection 15, which is formed between the front flange 25 and associated surfaces of the connection assembly 5 and preferably has a plurality of bores or openings in the front flange 25, a second coolant channel 16, which extends in a ring shape between the inner circumference of the stator 3 and the rotor 2, and a coolant outlet 17, which is formed by a plurality of bores on the bottom of the motor housing 4.The connection assembly 5 as a cover 18 prevents coolant from escaping from the coolant circuit 12 by fluid-tightly closing the motor housing 4. As shown by the arrows in Fig. 1 and 2, the coolant can either flow through the coolant inlet 13 into the coolant circuit 12 and from there via the annular first coolant channel 14, the coolant diverter 15 and the second annular coolant channel 16 to the coolant outlet 17, where the coolant exits the electric motor 1 again, or it can alternatively flow in the opposite direction through the coolant outlet 17, through the second coolant channel 16 and via the coolant diverter 15 and the first coolant channel to the coolant inlet 12, through which it then exits.In the first coolant channel 14 between the motor housing 4 and the outer circumference of the stator 3, the coolant absorbs the magnetization reversal and eddy current losses in the return path 7, while as it flows through the annular second coolant channel 14 in the gap between the rotor 2 and stator 3, the heat loss from the ohmic losses and eddy current losses in the stator winding 6 is dissipated. Since, when the electric motor 1 is subjected to high loads, the majority of the power loss and thus the waste heat occurs in the stator winding 6, the cross sections of the first coolant channel 14 and the second coolant channel 14 are dimensioned such that a turbulent flow is achieved in the region of the second coolant channel 16 for optimal heat transfer.Since thermal oil is used as the coolant for the electric motor 1, both the rolling bearing 10 in the connecting assembly 5 and the rolling bearing 9 at the bottom of the motor housing 4 are open to the second coolant channel 16. This fluid-open connection to the rolling bearings 9, 10 enables both cooling and the supply of the rolling bearings 9, 10 with a lubricant.

[0035] The perspective exploded view in Fig. 3 shows the motor housing 4, which is open at the front and houses the rotor 2 and stator 3, as well as the separate connection assembly 5. In addition to the actual end cover 18, the connection assembly 5 has three electrical connection lines 19, which are electrically connected to corresponding plug connection parts 21 of the stator winding 6 via associated plug connection means 20 during assembly of the connection assembly 5 on the motor housing 4. The connection assembly 5 also has a control line 22 with an associated plug for connecting the motor electronics (connection and / or commutation electronics) 28 of the electric motor 1. The connection assembly 5 can be plugged and fastened to the open side of the motor housing 4 with the end cover 18 during assembly of the electric motor 1.To securely seal the electric motor 1, in addition to a radial seal 23 on the inner circumference of the motor housing 4, an axial seal 24 can also be provided on the front flange of the motor housing 4. The use of an additional radial seal 23 in addition to a conventional axial seal 24 enables very high sealing of the electric motor 1 against the environment and also a high durability of the sealing function. The plug-in connection parts 21 connected to the stator winding 6 and the end of the rotor shaft 8 extend through the front flange 25, for fixing the stator 3 and supporting the rotor 2 via the rotor shaft 8 guided in the rolling bearing 10.

[0036] Fig. 4 shows a section through the connection assembly 5 fastened to the motor housing 4. The connection assembly 5 is seated with the associated connection cover 18 in the open end face of the cup-shaped motor housing 4, wherein the interior of the electric motor 1 is hermetically, i.e. fluid-tight, sealed from the environment by means of the radial seal 23 and the axial seal 24 in the region of the adjacent end cover 18. The connection lines 19 are connected to the plug-in connection means 20 via busbars 26. As can be clearly seen in the enlarged view in Fig. 4, the plug-in connection means 20 of the connection assembly 5 are designed as plug sockets 27 which are embedded in the housing of the connection assembly 5.In addition to being embedded in the housing of the connection assembly 5, an O-ring 35 is provided at the open end of the sockets 27 opposite the housing of the connection assembly 5, which improves the sealing of the sockets 27 and thus also the electrical connection to the busbar 26 and the connecting cable 19. The pin-shaped plug connection part 21, which extends from the stator winding 6 through the front flange 25, is received in the socket 27 and enables electrical contact with the stator winding 6 of the stator 3.

[0037] In addition to the end cover 18 with the embedded sockets 27, as well as the associated busbars 26 and connecting cables 19 for supplying power to the stator winding 6, the connection assembly 5 also includes the motor electronics 28, which here is embedded in the housing of the connection assembly 5 in the form of a housing with all components of the commutation electronics and a sensor 30, preferably a magnetic field-sensitive angular position sensor. The sensor 30 detects the magnetic field of a control magnet 31 mounted at the end of the rotor shaft 8 in order to control the operation of the electric motor 1.

[0038] During the manufacture of the connection assembly 5, in a first process step, the motor electronics 28, including the circuit board 29, the electronic components for commutation, the sensor 30, and the connections of the control line 22, are overmolded on all sides with a defined material thickness of a preferably thermoplastic or alternatively thermosetting plastic, for example, by thermoplastic injection molding, thermosetting transfer molding, or mold encapsulation. In a second process step, this component, along with the actual housing of the connection assembly 5, is again overmolded or encapsulated with a thermoplastic or thermosetting plastic to form the end cover 18, so that any holding positions from the first process step are also reliably sealed against the fluids in the electric motor 1.

[0039] As already shown in Fig. 3, the connection assembly 5 is detachably connected to the motor housing 4 by inserting the plug-in connection means 20 onto the plug-in connection parts 21 and the end cover 18 into the open end on the first side of the motor housing 4. In addition to the plug-in connection of the end cover 18 and the plug-in connection means 20, in the embodiment shown in Fig. 3, the connection assembly 5 can be detachably screwed into the motor housing 4 using screws 32 and corresponding threaded holes 33. Alternatively, the connection assembly 5 can also be connected to the motor housing 4 using a locking mechanism. This connection can also be designed to be non-detachable, for example by means of a locking mechanism or adhesive, in order to prevent the connection from becoming loose due to vibrations.

[0040] Fig. 5 shows a pre-assembled cable assembly 34 with three connecting cables 19, each connected to a busbar 26 and a socket 27. The busbars 26, made of copper, for example, can be connected to the sockets 27 by pressing, welding, or soldering. The connecting cables 19 can in turn be connected to the busbar 26 by welding or soldering. Furthermore, the individual connecting cables 19, busbars 26, and associated sockets 27 are combined to form a common cable assembly 34 so that the cable assembly 34 can be added to the connection assembly 5 during the second process step for producing the housing of the connection assembly 5 and forming the end cover 18.During the manufacturing process of the connection assembly 5, the plug sockets 27 are held by a molding tool in a position defined for connection to the plug connection parts 21, so that during subsequent assembly of the connection assembly 5 onto the motor housing 4, the plug sockets 27 precisely match the position of the plug connection parts 21 provided in the motor housing 4. List of reference symbols.

[0041] 1 electric motor

[0042] 2 rotors

[0043] 3 Stator

[0044] 4 engine housing

[0045] 5 Connection module

[0046] 6 Stator winding

[0047] 7 Conclusion

[0048] 8 Rotor shaft

[0049] 9 rolling bearings

[0050] 10 rolling bearings

[0051] 12 Coolant circuit

[0052] 13 Coolant inlet

[0053] 14 first coolant channel

[0054] 15 Coolant diversion

[0055] 16 second coolant channel

[0056] 17 Coolant drain

[0057] 18 end caps

[0058] 19 connecting cables

[0059] 20 connectors

[0060] 21 connector parts

[0061] 22 Control line

[0062] 23 radial seal

[0063] 24 axial seal

[0064] 25 front flange

[0065] 26 busbars

[0066] 27 sockets

[0067] 28 Motor electronics (connection and / or commutation electronics)

[0068] 29 circuit board

[0069] 30 sensors

[0070] 31 control magnets

[0071] 32 screws

[0072] 33 threaded holes

[0073] 34 Cable assembly

[0074] 35 O-ring

Claims

Claims Electronically commutated electric motor (1) with a liquid-cooled stator (3) having an ironless hollow cylindrical stator winding (6) and a coolant circuit (12) for passing a coolant through the electric motor (1), a rotor (2) rotatably arranged concentrically to the stator (3), a motor housing (4) accommodating the stator (3) and the rotor (2), a connection assembly (5) and at least one electrical connection lead (19) for electrically connecting the stator winding (6), characterized in that the connection assembly (5) has a cover (18) and at least one plug connector (20) for electrically contacting the electrical connection lead (19) with a corresponding plug connector (21) of the stator winding (6) of the stator (3), and that the connection assembly (5) provides a fluid-tight seal for the motor housing (4),wherein a sealing element is provided between the connector (20) and a housing of the connection assembly (5). Electric motor (1) according to claim 1, characterized in that the stator (3) has a stator winding (6) with three stator winding phases and three connector parts (21) each connected to a stator winding phase, which are positioned on the first side of the motor housing (4), and the connection assembly (5) has three connectors (20) each connected to an electrical connecting lead (19). Electric motor (1) according to claim 1 or 2, characterized in that the connector (20) of the connection assembly (5) is designed as a socket (27) and the corresponding connector part (21) of the stator winding (6) is preferably designed as a contact pin. Electric motor (1) according to claim 3, characterized in thatthat an O-ring (35) is provided as a sealing element between the socket (27) and a housing of the connection assembly (5). Electric motor (1) according to one of claims 1 to 4, characterized in that a radial seal (23) is provided between the connection assembly (5) and the motor housing (4). An electric motor (1) according to any one of claims 1 to 5, characterized in that a cable assembly (34) is provided, wherein the cable assembly (34) comprises the electrical connecting cable (19), the connector (20), and at least one busbar (26) for the electrical connection of the electrical connecting cable (19) to the connector (20). An electric motor (1) according to claim 6, characterized in that the cable assembly (34) comprises three electrical connecting cables (19), three sockets (27), and three busbars (26), wherein the three electrical connecting cables (19), the three sockets (27), and the three busbars (26) are mechanically connected to one another.An electric motor (1) according to any one of claims 1 to 7, characterized in that the connection assembly (5) is made of a thermoplastic or thermoset plastic by injection molding or potting, wherein connection electronics with the electrical connection cable (19) and the connector (20) are embedded in the connection assembly (5). An electric motor (1) according to claim 8, characterized in that commutation electronics for commutation of the electric motor (1) are provided, wherein the commutation electronics are embedded in the connection assembly (5). An electric motor (1) according to claim 9, characterized in that the commutation electronics have an integrated sensor (30), preferably a magnetic field-sensitive angle position sensor, which in particular detects the magnetic field of a diametrical control magnet (31) mounted at the end of a rotor shaft (8).Electric motor (1) according to one of claims 8 to 10, characterized in that the connection electronics and / or the commutation electronics are provided with an additional layer of a thermoplastic or thermosetting plastic, which is applied in a prior step by means of injection molding, transfer pressing or potting. An electric motor (1) according to any one of claims 1 to 11, characterized in that the coolant circuit (12) for conveying a coolant through the electric motor (1) comprises a first coolant channel (14) between the motor housing (4) and the outer circumference of the stator (3), a second coolant channel (16) between the inner circumference of the stator (3) and the rotor (2), and a coolant deflection (15) for fluid connection between the first coolant channel (14) and the second coolant channel (16), wherein the coolant deflection (15) is preferably formed, at least partially, by the connection assembly (5). An electric motor (1) according to claim 12, characterized in that the second coolant channel (16) between the inner circumference of the stator (3) and the rotor (2) has a smaller cross-sectional area than the first coolant channel (14) between the motor housing (4) and the outer circumference of the stator (3).An electric motor (1) according to claim 12 or 13, characterized in that the coolant circuit (12) has a coolant inlet (13) arranged on the circumference of the motor housing (4) to the first coolant channel (14), and preferably has a coolant outlet (17) from the second coolant channel (16) which is arranged on a second side of the motor housing (4) opposite the connection assembly (5). A connection assembly (5) for an electronically commutated electric motor (1) according to one of claims 1 to 14, wherein the connection assembly (5) comprises an end cover (18) of the electronically commutated electric motor (1) and at least one electrical connection cable (19), at least one plug connector (20) for electrically contacting the stator winding (6) with the electrical connection cable (19), and a sealing element between the plug connector (20) and a housing of the connection assembly (5).

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