Motor unit with reduced friction

Abstract

Motor unit (1) with an electric motor (11) which is arranged in a housing (12), wherein the motor unit (1) comprises a lubricant circuit which lubricates and cools the electric motor (11), wherein- the electric motor (11) comprises a stator (111) and a rotor (112) which is rotatably mounted in the stator (111) which is rigidly connected to the housing (12), wherein a rotor gap (RS) is located between the stator (111) and the rotor (112), wherein the stator (111) is at least partially surrounded by a stator housing (121) which is arranged within the housing (12), wherein the stator housing (121) is at least partially filled with lubricant and belongs to the lubricant circuit,- at least one lubricant pump (13) which is fluidically connected to the stator housing (121) and receives lubricant from the stator housing (121), wherein the lubricant pump (13) has at least one has an outlet for lubricant,which is fluidly connected to the stator (111) and the rotor (112), wherein the lubricant pump (13) delivers lubricant to the electric motor (11) via the outlet, characterized in that a flow generation unit (15) is provided, which sucks air from the housing (12) and blows it into the rotor gap (RS) in order to remove lubricant from the rotor gap (RS) in order to reduce the internal friction in the electric motor (11), wherein the rotor (112) forms a pump of the flow generation unit (14) and, during its rotation, delivers air into the rotor gap (RS) or to the rotor gap (RS), wherein the flow generation unit (15) comprises an oil separator (151) which is arranged in front of the rotor (112) in the direction of flow of the air through the flow generation unit (15),wherein the oil separator (151) separates lubricant contained in the air in the housing (12) and passes air with reduced lubricant content or lubricant-free air to the rotor (112) acting as a pump.

Description

[0001] The invention relates to a motor unit with an electric motor which is arranged in a housing, wherein the motor unit comprises a lubricant circuit which lubricates and cools the electric motor, wherein the electric motor comprises a stator and a rotor which is rotatably mounted in the stator which is rigidly connected to the housing, wherein a rotor gap is located between the stator and the rotor. The motor unit further comprises a lubricant pump which is fluidically connected to the stator housing and a flow generation unit which sucks air from the housing and blows it into the rotor gap in order to remove lubricant from the rotor gap and thus reduce the internal friction in the electric motor. The invention further relates to a method for reducing the internal friction in a motor unit.

[0002] Lubricants such as lubricating oil are often used to cool and lubricate electric motors in a motor unit. To ensure long-term, safe operation of the motor unit, the lubricant must be circulated through the electric motor. In this way, the lubricant in the electric motor absorbs heat and releases it elsewhere in the motor unit. To ensure operational reliability under all load conditions, a dry sump lubrication system can be used, for example. This system extracts lubricant from the electric motor or a connected gearbox and stores it in a lubricant tank. From this lubricant tank, the lubricant is then fed back to the electric motor and other components of the motor unit at varying pressure levels.This concept ensures reliable lubrication of all components under all load conditions, but is complex and requires numerous components. Due to the circulation of the lubricant in the motor unit, lubricant also reaches the rotor gap between the stationary stator and the rotating rotor of the electric motor. The lubricant in the rotor gap causes friction losses in the electric motor, which leads to increased electrical energy consumption and additional heating of the electric motor.

[0003] US 2021 / 0 083 555 A1 describes a method for reducing friction in a rotor gap caused by lubricant contained therein. In this method, a pump located in the housing of the electric motor is used to generate an air flow that removes the lubricant from the rotor gap.

[0004] DE 27 24 420 A1 describes a gas-cooled engine unit. The rotor has gas inlets, gas outlets, and channels arranged between them. As the rotor rotates, cooling gas is drawn in from the rotor through the gas inlets, guided through the channels, and then, after heat transfer from the rotor to the cooling gas, expelled through the gas outlets.

[0005] WO 2004 / 070919 A1 describes a cooling system for an electric motor. This gas-cooled electric motor is cooled by an axial pump mounted on the rotor shaft that pumps cooling gas longitudinally through the rotor gap.

[0006] The generic document WO 2020 / 067 259 A1 describes a drive device with an electric motor and a gearbox. The rotor shaft is hollow inside, and a gearbox axis is arranged coaxially with the rotor shaft in its interior. The drive device has an oil circuit provided for lubrication and cooling. Part of the oil is guided through the space between the rotor shaft and the gearbox axis arranged therein with the aid of a special device.

[0007] JP 2003-250248 A describes an electric motor with reduced internal friction. The electric motor is cooled internally by oil that flows through both the stator and the rotor. To remove oil from the rotor gap between the stator and rotor, an impeller is mounted on the rotor, which generates an airflow that flows through the rotor gap in a direction parallel to the rotor axis. This airflow removes oil from the rotor gap.

[0008] The object of the invention is to propose solutions with which the friction generated by lubricants in an electric motor can be reduced, while at the same time reducing the complexity of the structure of a motor unit surrounding the electric motor.

[0009] This object of the invention is achieved by a motor unit with an electric motor which is arranged in a housing, wherein the motor unit comprises a lubricant circuit which lubricates and cools the electric motor, wherein - the electric motor comprises a stator and a rotor which is rotatably mounted in the stator which is firmly connected to the housing, wherein a rotor gap is located between the stator and the rotor, wherein the stator is at least partially surrounded by a stator housing which is arranged within the housing, wherein the stator housing is at least partially filled with lubricant and belongs to the lubricant circuit, - at least one lubricant pump which is fluidically connected to the stator housing and receives lubricant from the stator housing, wherein the lubricant pump has at least one outlet for lubricant which is fluidically connected to the stator and the rotor, wherein the lubricant pump conveys lubricant to the electric motor via the outlet.According to the invention, a flow generation unit is further provided which sucks air from the housing and blows it into the rotor gap in order to remove lubricant from the rotor gap in order to reduce the internal friction in the electric motor, wherein the rotor forms a pump of the flow generation unit and conveys air into the rotor gap or to the rotor gap as it rotates, wherein the flow generation unit comprises an oil separator which is arranged in front of the rotor in the flow direction of the air through the flow generation unit, wherein the oil separator separates lubricant present in the air in the housing and passes air with a reduced lubricant content or lubricant-free air on to the rotor acting as a pump.

[0010] The motor unit according to the invention comprises an electric motor with a stator and a rotor, which are arranged in a housing. The motor unit comprises a lubricant circuit, which on the one hand lubricates the moving parts and thus protects them from wear and on the other hand cools the motor unit, in particular the electric motor, during operation. In the following, the term lubricant is always used, which can also be referred to as coolant. The stator is accommodated in a stator housing, which forms a partial region of the housing. The stator housing can be separated from the other housing regions, in particular the region of the housing in which the rotor is located. However, it is also possible for the stator housing and the remaining region of the housing to merge into one another and form a common cavity. Lubricant is always present inside the stator housing.The stator housing thus forms a reservoir for lubricant, which is arranged inside the housing and at least partially contains lubricant when the electric motor is in operation. In this way, no additional tank for lubricant is required outside the housing. However, such an externally arranged lubricant tank can be provided in some embodiments. In addition to the stator housing, the lubricant circuit includes a lubricant pump, which takes in lubricant from the stator housing and transports it back to the stator and rotor via an outlet. The term “taking in lubricant by the lubricant pump” means that the lubricant pump either sucks in lubricant or the lubricant is pumped to or into the lubricant pump by excess pressure in other areas of the motor unit, for example in the stator housing.Inside the electric motor, the lubricant absorbs heat and thus cools the electric motor. As the lubricant is transported through the electric motor, lubricant always gets into the rotor gap, which extends circumferentially around the rotor between the rotor and stator. The lubricant can get into the rotor gap in various ways: in a so-called wet-lubricated electric motor, the lubricant intentionally flows through all areas of the electric motor, including the stator and rotor. In this way, heat is effectively dissipated from all areas of the electric motor, but lubricant also inadvertently penetrates the rotor gap. In electric motor designs in which the stator housing is at least partially sealed from the rest of the housing, some lubricant usually also inadvertently penetrates through the seal of the stator housing and into the rotor gap.Such leaks are difficult to prevent from the design of an electric motor. Furthermore, it is possible for lubricant to leak from the rotor, particularly from its laminated cores, at higher rotor speeds and into the rotor gap. Finally, it is possible for lubricant added to the bearings of the rotor shaft to penetrate from the bearings into the rotor gap. When the rotor rotates, friction occurs due to lubricant in the rotor gap, which reduces the efficiency of the electric motor and thus the motor unit. In order to remove lubricant that has penetrated the rotor gap, the motor unit includes a flow generation unit that injects air into the rotor gap and thereby removes any lubricant contained therein. The rotor of the electric motor forms the pump of the flow generation unit, which generates the air flow.Due to its rotating movement, the rotor acts like a flow pump and pumps air from the housing into the rotor gap. The rotor, which naturally rotates when the electric motor is in operation, is also used functionally as a pump for the air flow. In this way, the number of components required in the motor unit is not increased, but at the same time the flow generation unit according to the invention significantly reduces the internal friction in the electric motor. The air flow generated by the rotor removes at least the majority of the lubricant from the rotor gap. At the same time, the air flow in the rotor gap causes an increase in pressure in the part of the housing in which the rotor is located. This increase in pressure, in turn, causes the amount of lubricant flowing in the electric motor towards the rotor gap to be reduced. This already reduces the flow of lubricant into the rotor gap.The motor unit may include further components, which are described in more detail in the embodiments.

[0011] According to the invention, the flow generation unit comprises an oil separator which is arranged upstream of the rotor in the direction of air flow through the flow generation unit, wherein the oil separator separates lubricant contained in the air in the housing and directs air with a reduced lubricant content or lubricant-free air to the rotor acting as a pump. In this embodiment, an oil separator is provided which removes lubricant from the intake air. The air in the housing usually contains lubricant during operation of the motor unit. The provision of an oil separator ensures that the rotor does not introduce additional lubricant into the rotor gap via the injected air. In this context, an oil separator is understood to mean all components which remove lubricant from an air flow.

[0012] In a further embodiment, the rotor comprises a rotor shaft which is rotatably mounted in the housing, wherein the rotor acting as a pump of the flow generation unit sucks in air axially to the rotor shaft through at least one end region of the rotor shaft and conveys this sucked in air radially to the rotor shaft to the rotor gap, wherein the rotor acts like a flow pump. In this embodiment, the air flow in the flow generation unit is guided partially through the rotor shaft. The air flow is guided at at least one end in the axial or radial direction into the interior of the rotor shaft and transported therein in the axial direction. The air flow is then guided radially to the rotor shaft through the rotor and thus reaches the rotor gap. The rotating rotor acts as a flow pump by accelerating the air in the rotor so that it flows out of the rotor into the rotor gap.

[0013] Furthermore, it is provided that the air outlet of the flow generation unit is arranged essentially in the center of the rotor in the axial direction to the rotor shaft, the air flows axially to the rotor shaft in two opposite directions through the rotor gap, or the air outlet is arranged axially to the rotor shaft in an edge region of the rotor, with the air flowing axially to the rotor shaft in one direction through the rotor gap. The air outlet of the flow generation unit is located on the outer surface of the rotor. In the axial direction to the rotor shaft, the air outlet can be arranged in the center of the rotor. The air flowing from the air outlet is pumped through the rotor gap in two opposite directions, thus removing any lubricant located there. If the air outlet is arranged in the center, the air flow is guided through the laminated core of the rotor.Alternatively, the air outlet can be arranged in an edge area axially directed toward the rotor shaft, particularly outside the rotor's laminated core. With this arrangement, the air flow emerging from the air outlet flows in only one direction through the rotor gap. Arranging the air outlet in the laminated core has the advantage that the air flow also acts as a cooling element. Arranging the air outlet in an edge area of ​​the rotor is structurally simpler, as no lines or ducts for the air are required in the rotor's laminated core.

[0014] In a further embodiment, the interior of the stator housing not occupied by the stator is at least two-thirds filled with lubricant. In this embodiment, the stator housing can be at least partially sealed from the rest of the housing, for example by means of sheet metal. The stator housing contains the stator and an additional hollow interior. This hollow interior is used as a reservoir or tank for lubricant. During operation of the motor unit, the hollow interior in the stator housing is always at least two-thirds filled with lubricant. It is also possible for the hollow interior to be completely filled with lubricant. During operation of the electric motor, the lubricant level in the stator housing can fluctuate. In this embodiment, there is preferably an overpressure in the stator housing, which drives some of the lubricant contained therein to the lubricant pump, which then absorbs it.

[0015] In a further embodiment, it is provided that a gear is provided which is coupled to the rotor, wherein the gear is arranged in a gear housing which forms a partial region of the housing, wherein a shell is provided in the gear housing which seals one or more gears against a lubricant reservoir at least in regions, wherein the lubricant reservoir is formed by a partial region of the gear housing arranged at the bottom in the gear housing, wherein the lubricant reservoir is part of the lubricant circuit and the lubricant pump is fluidically connected to the lubricant reservoir, sucks lubricant from the lubricant reservoir and the outlet of the lubricant pump is fluidically connected to the gear, wherein the lubricant pump delivers lubricant to one or more gears via its outlet.In this embodiment, the motor unit also comprises a gearbox connected to the electric motor. The gearbox is housed in a portion of the housing, the gearbox housing, and comprises at least one gear that is operatively connected to the rotor shaft. The lower portion of the gearbox housing forms a lubricant reservoir in which lubricant collects. The at least one gear is sealed off from the lubricant reservoir by a shell, so that the gear does not immerse itself in the lubricant in the lubricant reservoir during operation. In this embodiment, the lubricant reservoir is connected to the inlet of the lubricant pump. The lubricant pump thus also draws lubricant from the lubricant reservoir and transports it through its outlet to the at least one gear of the gearbox. In this way, the lubricant circuit also extends to the gearbox.Preferably, the same lubricant is used for lubrication and cooling of the electric motor and gearbox, which is transported by a single lubricant pump.

[0016] It is further provided that the lubricant reservoir is fluidically connected to the stator housing and lubricant flows from the stator housing to the lubricant reservoir, wherein the lubricant pump receives lubricant from the lubricant reservoir and, via the fluidic connection between the stator housing and the lubricant reservoir, from the stator housing. In this embodiment, the stator housing and the lubricant reservoir in the transmission housing are fluidically connected to one another. Such a fluidic connection can be provided, for example, via a line. In this embodiment, the stator housing and the lubricant reservoir together form a storage container or tank for the lubricant. The lubricant pump can suck lubricant from both the lubricant reservoir and the stator housing.Alternatively, the lubricant pump can only be connected to one of the stator housing or lubricant reservoir to suck in lubricant.

[0017] Optionally, the flow generation unit includes an auxiliary pump, which, as needed or in addition to the rotor, draws air from the housing and injects it into the rotor gap. In this embodiment, in addition to the rotor acting as a pump, an auxiliary pump is provided to generate an air flow. This auxiliary pump can inject additional air into the rotor gap as needed, i.e., for a limited time. Such a need for additional air flow can be useful, for example, before the electric motor is started up or when the electric motor is operating at low rotor speeds, in order to effectively remove lubricant from the rotor gap.

[0018] In a further embodiment, a return line is provided which connects the rotor gap to the stator housing and / or the lubricant reservoir, wherein the return line of the flow generation unit guides air blown through the rotor gap into the lubricant and this air passes through the lubricant back into the housing, in particular into the gearbox housing. The air blown into the rotor gap by the flow generation unit leaves the rotor gap and flows back into the housing, in particular into the housing area around the rotor. To return this air, which may contain lubricant after its journey through the rotor gap, a return line is provided which leads from the rotor gap or from a housing area near the rotor gap to the stator housing and / or to the lubricant reservoir.The connection of the return line is designed such that the transported air is directed into the lubricant in the stator housing and / or lubricant reservoir, where it rises within the lubricant. At least a portion of the lubricant contained in the transported air is released into the lubricant reservoir. Alternatively, the return line can be designed or arranged such that the returned air exits not into the lubricant but above the lubricant level in the housing. This prevents the formation of bubbles in the lubricant. In this alternative embodiment, the outlet opening of the return line is arranged above the lubricant level in the lubricant reservoir or in the stator housing.

[0019] The object of the invention is further achieved by a method for reducing the internal friction in a motor unit according to one of the previously described embodiments, comprising the steps of A) sucking air from the housing through the flow generation unit, wherein the rotor forms a pump of the flow generation unit, B) blowing the air into the rotor gap through the flow generation unit, wherein lubricant is removed from the rotor gap by this blown-in air and thus the internal friction in the electric motor is reduced.

[0020] The method according to the invention removes at least a large portion of the lubricant located in the rotor gap of an electric motor. This significantly reduces the internal friction between the rotor and stator in the electric motor. The method is carried out in the specified order of process steps A) and B). During operation of the motor unit, process steps A) and B) are continuously repeated and occur simultaneously.

[0021] In a first process step, the flow generation unit of the motor unit draws air from the housing. The rotating rotor acts as a flow pump, drawing in the air.

[0022] In a second process step B), the sucked-in air is blown into the rotor gap. This blowing is also carried out by the electric motor's rotor, which acts as a pump. The injected air ultimately displaces lubricant in the rotor gap, thus reducing internal friction in the electric motor.

[0023] The method according to the invention reduces friction in the electric motor by removing lubricant from the rotor gap. Because the rotor is used as the driving pump to remove the lubricant, no additional pump is required to generate the air flow. The method requires few components for its implementation and is also capable of long-term stability.

[0024] Features, effects, and advantages disclosed in connection with the motor unit are also deemed to be disclosed in connection with the method. The same applies in reverse: features, effects, and advantages disclosed in connection with the method are also deemed to be disclosed in connection with the motor unit.

[0025] The invention is schematically illustrated in the drawing using an embodiment and will be further described with reference to the drawing. In the drawings: Fig. 1 shows a schematic view of an embodiment of a motor unit according to the invention, Fig. 2 shows a schematic view of an alternative embodiment of a motor unit according to the invention.

[0026] Fig. 1 shows a schematic view of an embodiment of a motor unit 1 according to the invention. The illustrated motor unit 1 comprises an electric motor 11, shown on the right, which is mechanically coupled to a gearbox 14, shown on the left. During operation, the rotor shaft 1121 transmits torque to the gearbox 14, which converts the rotary motion and outputs it via an output shaft (not shown). The gearbox 14 is optional; the rotor shaft 1121 can also be used directly as an output shaft. The motor unit 1 is housed in a housing 12 having several subregions. The stator 111 of the electric motor 11 is arranged in a stator housing 121. The stator housing 121 is separated and / or sealed from the subregion of the housing 12 in which the rotor 112 is arranged.The rotor 112 is located inside the stator 111 and, in the illustrated embodiment, is rotatably mounted in the housing 12 via two bearings arranged outside the rotor 112. Between the rotor 112 and the stator 111 there is a rotor gap RS which extends circumferentially around the rotor shaft 1121. The gear 14 comprises a plurality of gears, only one of which is shown schematically. The gear 14 is arranged in a gear housing 122 which belongs to the housing 12. The gear housing 112 is connected inside the housing 12 to the partial area in which the rotor 112 is arranged. The lower area of ​​the gear housing 112 in the illustration forms a lubricant reservoir R which contains lubricant. The lubricant is used in the motor unit 1 both to lubricate the moving parts and to cool the electric motor 11.Inside the gear housing 112 there is also a shell S which seals the illustrated gear against the lubricant in the lubricant reservoir R. During operation of the motor unit 1, lubricant is also applied to the gear through the outlet of the lubricant pump 13, which, however, is thrown off by centrifugal forces during the rotation of the gear and then collects in the lubricant reservoir R. The shell S prevents the gear from coming into contact with the lubricant in the lubricant reservoir R during its rotation. In this way, the gear does not pump any lubricant from the lubricant reservoir R during its rotation. The motor unit 1 comprises a lubricant circuit in which the stator housing 121 and the lubricant reservoir R serve as a reservoir or tank for the lubricant.In this way, no separate tank or reservoir for lubricant is required, which reduces the complexity of the motor unit 1. The stator housing 121 is at least partially filled with lubricant. Preferably, at least two-thirds of the interior space of the stator housing 121 not occupied by the stator 111 is filled with lubricant. In the illustrated embodiment, the entire hollow interior of the stator housing 121 is completely filled with lubricant. The lubricant in the stator housing 121 is in motion and flows through the stator 111, thereby cooling it. In the illustrated embodiment, the stator housing 121 is fluidly connected to the lubricant reservoir R. This means that lubricant can flow, for example via channels, from the stator housing 121 to the lubricant reservoir R or vice versa. The lubricant circuit also includes the lubricant pump 13, which is arranged outside the housing 12 in the illustration.The lubricant pump 13 is fluidically connected to the lubricant reservoir R via a line and draws lubricant from it. The lubricant pump also indirectly draws lubricant from the stator housing 121 via the fluidic connection between the lubricant reservoir R and the stator housing 121. The lubricant pump 13 also has an outlet, which in turn is fluidly connected via lines to the gearbox 14, the stator housing 121, and the rotor shaft 1121. Via the outlet, the lubricant pump 13 delivers lubricant to the gears, the stator 111, and the rotor 112, thereby both lubricating and cooling these components. Optionally, a heat exchanger can be arranged in the connecting line between the lubricant pump 13 and the other components, which cools the lubricant before it is fed to the motor unit 1.

[0027] The motor unit 1 further comprises a flow generation unit 15. This flow generation unit 15 is provided for generating an air flow and directing it into the rotor gap RS or towards the rotor gap RS. The air flow displaces lubricant or lubricant mist from the rotor gap RS and thus reduces the internal friction of the electric motor 11 between the rotor 112 and the stator 111. According to the invention, the rotor 112 serves as a pump of the flow generation unit 15, which generates the air flow into the rotor gap RS. In this way, the rotor 112, in addition to its function as the output element of the electric motor 11, fulfills a further function, namely that of reducing the friction in the rotor gap RS. Due to this combination of functions, no additional pump is required to generate the air flow, thereby reducing the complexity and number of components of the motor unit 1.As it rotates, the rotor 112 draws in air from the housing 12 in the left-facing end region of its rotor shaft 1121 and initially directs it within the rotor shaft 1121. In the illustrated embodiment, the rotor 112 draws in air from the end face of the rotor shaft 1121 facing toward the gearbox 14. The rotor 112 conveys the air drawn in in the axial direction toward the rotor shaft 1121 in a radial direction toward the rotor shaft 1121 to the rotor gap RS. The air outlet of the flow generation unit 15 is located on the outer circumferential surface of the rotor 112, which forms a boundary of the rotor gap RS. In the illustrated embodiment, the air outlet is arranged substantially in the middle of the length of the rotor shaft 1121.Starting from the air outlet, the air flow generated by the flow generation unit 15 flows in a direction axial to the rotor shaft 1121 to the left and to the right through the rotor gap RS, thereby removing any lubricant that has penetrated into the rotor gap RS. In the embodiment shown, the air is guided through the laminated core of the rotor 112. Alternatively, the air outlet can also be arranged in an end region of the rotor 112 in the axial direction, in particular outside the laminated core. With such an arrangement of the air outlet in the end region, the generated air flow then flows axially to the rotor shaft 1121 in only one direction through the rotor gap RS. The prerequisite for such an air flow in only one direction is that there is an overpressure on the side of the rotor shaft 1121 on which the air exits the rotor 112.Such generation of overpressure on one side of the rotor shaft 1121 can be achieved, for example, by sealing the rotor gap RS on this side with respect to the housing 12. As it rotates, the rotor 112 acts like a flow pump, exerting centrifugal forces on the air within the rotor. This generates an air flow, and further air is drawn in in the axial direction through the rotor shaft 1121. Optionally, the rotor 112 or the rotor shaft 1121 can also have additional elements that generate an air flow. Such additional elements can, for example, be guide vanes that generate an air flow in the axial direction toward the rotor shaft 1121. Furthermore, it is possible to provide an additional pump, which also generates an air flow, in addition to the pump formed by the rotor 112.Such an additional pump can increase the air flow, particularly at low speeds of the rotor 112, and thus effectively remove lubricant from the rotor gap RS. In the illustrated embodiment, the flow generation unit 15 further comprises an oil separator 151, which is arranged upstream of the rotor 112 in the direction of air flow. This oil separator 151 removes lubricant from the air drawn from the housing 12. In this way, the flow generation unit 15 prevents lubricant from being pumped into the rotor gap RS. After flowing through the rotor gap RS, the air flow is permeated with lubricant and flows back into the housing 12. In the illustrated embodiment, a return line RL is provided, which runs from the partial area of ​​the housing 12 in which the rotor 112 is located and in which the air flow leaves the rotor gap RS, to the lubricant reservoir R in the transmission housing 122.In the lubricant reservoir R, the returned air is passed through the lubricant, whereby a large proportion of the lubricant contained in the air flow remains in the lubricant reservoir R.

[0028] Fig. Figure 2 shows a schematic view of an alternative embodiment of a motor unit according to the invention. In this alternative embodiment, the motor unit 1 has a Fig. 1 shown embodiment has a different lubricant circuit. Fig. 2, the electric motor 11 is a wet-lubricated electric motor 11. Unless otherwise described, the components of the Fig. 2 described embodiment, which corresponds to the embodiment in Fig. 1, refer to the description Fig. 1. The Fig. The embodiment shown in Figure 2 comprises a housing 12. This housing in turn comprises a partial area in which the stator 11 is arranged, which is referred to as stator housing 121. The gear 14 is arranged in a gear housing 122, which also forms a partial area of ​​the housing 12. The stator housing 121 is not sealed off from the other housing areas, but merges into the housing area in which the rotor 112 is arranged and into the gear housing 122. In the Fig. In the embodiment shown in Figure 2, a lubricant tank T is provided, which is arranged outside the housing 12. For lubrication and cooling, lubricant is sucked from the lubricant tank T by the auxiliary pump 13z and supplied to the gearbox 14, the stator 111, the rotor 112, and the bearings of the rotor shaft 1121. This supply of cool lubricant takes place, for example, via the splash rings SR, which distribute the lubricant evenly over the aforementioned components. The lubricant moves through the electric motor 11 and collects due to gravity in the lower part of the stator housing 121. Thus, in this embodiment, the stator housing 121 is also at least partially filled with lubricant. The gearbox housing 122, the lower region of which lies below the lower region of the stator housing 121, is fluidly connected to the stator housing 121.In this lower area of ​​the gear housing 122, both lubricant that has absorbed heat in the electric motor 11 and lubricant that drips from the gear 14 collect. From this lower area of ​​the gear housing 122, the lubricant pump 13 sucks in lubricant and pumps it back into the lubricant tank T. Thus, the lubricant pump 13 also indirectly sucks in lubricant from the stator housing 121. Alternatively, it would be possible not to arrange a lubricant tank T outside the housing 12, but instead to arrange a lubricant sump in the lower area of ​​the gear housing 122 or in the lower area of ​​the stator housing 121, from which the lubricant pump 13 sucks in lubricant and then pumps it back to the gear 14 and the electric motor 11. The illustrated wet lubrication of the motor unit 1 means that lubricant is present almost everywhere in the housing 12.This ensures very efficient heat dissipation. The lubricant removal system shown in . Fig. 2, a flow generation unit 15 which uses the rotation of the rotor 112 to generate an air flow which is blown into the rotor gap RS. In this embodiment, too, the rotor 112 forms the pump of the flow generation unit 15. Thus, in the embodiment shown, the internal friction in the electric motor 11 generated by the lubricant in the rotor gap RS is significantly reduced, while at the same time the motor unit 1 is of simple construction. The embodiment in Fig.2 includes an optional oil separator 151, which removes lubricant from the air drawn in by the flow generation unit 15. In principle, a flow generation unit 15 can be used in all motor units 1 that are at least partially lubricated and / or cooled by a lubricant circuit, since the presence of lubricant in an electric motor 11 always causes lubricant to penetrate into the rotor gap RS. LIST OF REFERENCE SYMBOLS: 1 motor unit 11 Electric motor 111 Stator 112 Rotor 1121 rotor shaft 13 Lubricant pump 13z auxiliary pump 14 gearboxes 15 Flow generation unit 151 oil separators R Lubricant reservoir RS rotor gap RL return line S bowl SR squirt ring T Lubricant tank

Claims

[1] Motor unit (1) with an electric motor (11) which is arranged in a housing (12), wherein the motor unit (1) comprises a lubricant circuit which lubricates and cools the electric motor (11), wherein - the electric motor (11) comprises a stator (111) and a rotor (112) which is rotatably mounted in the stator (111) which is fixedly connected to the housing (12), wherein a rotor gap (RS) is located between the stator (111) and the rotor (112), wherein the stator (111) is at least partially surrounded by a stator housing (121) which is arranged within the housing (12), wherein the stator housing (121) is at least partially filled with lubricant and belongs to the lubricant circuit, - at least one lubricant pump (13) which is fluidically connected to the stator housing (121) and receives lubricant from the stator housing (121), wherein the lubricant pump (13) has at least one outlet for lubricant which is fluidically connected to the stator (111) and the rotor (112), wherein the lubricant pump (13) conveys lubricant to the electric motor (11) via the outlet, characterized by , that a flow generation unit (15) which sucks air from the housing (12) and blows it into the rotor gap (RS) is provided to remove lubricant from the rotor gap (RS) in order to reduce the internal friction in the electric motor (11), wherein the rotor (112) forms a pump of the flow generation unit (14) and, during its rotation, conveys air into the rotor gap (RS) or to the rotor gap (RS), wherein the flow generation unit (15) comprises an oil separator (151) which is arranged in front of the rotor (112) in the flow direction of the air through the flow generation unit (15), wherein the oil separator (151) separates lubricant present in the air in the housing (12) and passes air with a reduced lubricant content or lubricant-free air on to the rotor (112) acting as a pump. [2] Motor unit (1) according to claim 1, wherein the rotor (112) comprises a rotor shaft (1121) which is rotatably mounted in the housing (12), wherein the rotor (112) acting as a pump of the flow generation unit (15) sucks in air axially to the rotor shaft (1121) through at least one end region of the rotor shaft (1121) and conveys this sucked-in air radially to the rotor shaft (1121) to the rotor gap (RS), wherein the rotor acts like a flow pump. [3] Motor unit (1) according to one of the preceding claims 1 to 2, in which the air outlet of the flow generation unit (15) is arranged in the axial direction to the rotor shaft (1121) substantially in the center of the rotor (112) and the air flows axially to the rotor shaft (1121) in two opposite directions through the rotor gap (RS) or the air outlet is arranged axially to the rotor shaft (1121) in an edge region of the rotor (112), the air flowing axially to the rotor shaft (1121) in one direction through the rotor gap (RS). [4] Motor unit (1) according to one of the preceding claims 1 to 3, in which the interior of the stator housing (121) not occupied by the stator (111) is at least 2 / 3 filled with lubricant. [5] Motor unit (1) according to one of the preceding claims 1 to 4, in which a gear (14) is provided which is coupled to the rotor (112), wherein the gear (14) is arranged in a gear housing (122) which forms a partial region of the housing (12), wherein a shell (S) is provided in the gear housing (122) which seals one or more gears against a lubricant reservoir (R), at least in some regions, wherein the lubricant reservoir (R) is formed by a partial region of the gear housing (122) arranged at the bottom in the gear housing (122), wherein the lubricant reservoir (R) is part of the lubricant circuit and the lubricant pump (13) is fluidically connected to the lubricant reservoir (R), sucks lubricant from the lubricant reservoir (R), and the outlet of the lubricant pump (13) is fluidically connected to the gear (14),wherein the lubricant pump (13) delivers lubricant to one or more gears via its outlet., [6] Motor unit (1) according to claim 5, wherein the lubricant reservoir (R) is fluidically connected to the stator housing (121) and lubricant flows from the stator housing (121) to the lubricant reservoir (R), wherein the lubricant pump (13) receives lubricant from the lubricant reservoir (R) and from the stator housing (121) via the fluidic connection between the stator housing (121) and the lubricant reservoir (R). [7] Motor unit (1) according to one of the preceding claims 1 to 6, in which the flow generation unit (15) comprises an additional pump which, as required or in addition to the rotor (112), sucks air from the housing (12) and blows it into the rotor gap (RS). [8] Motor unit (1) according to one of the preceding claims 1 to 7, in which a return line (RL) is provided which connects the rotor gap (RS) to the stator housing (121) and / or the lubricant reservoir (R), wherein the return line (RL) guides the air blown by the flow generation unit (15) through the rotor gap (RS) into the lubricant and this air passes through the lubricant back into the housing (12). [9] Method for reducing internal friction in an engine unit (1) according to one of the preceding claims, comprising the steps A) Suction of air from the housing (12) by the flow generation unit (15), wherein the rotor (112) forms a pump of the flow generation unit (15), B) Blowing the air into the rotor gap (RS) through the flow generation unit (15), whereby this blown-in air removes lubricant from the rotor gap (RS) and thus reduces the internal friction in the electric motor (11).

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