Electric machine

Abstract

The invention relates to an electric machine (10) comprising a stator (11) and a fluid conduit (20), wherein the fluid conduit (20) is arranged, together with the stator lamination (21), to form a flow space (22) for a fluid (F) such that stator windings (24) of the stator (11) can be surrounded by the fluid (F) which can be introduced into the flow space (22) through at least one fluid supply opening (23).

Description

[0001] The invention relates to an electrical machine comprising a stator and a fluid line device, wherein the fluid line device has at least one fluid supply opening and is designed, together with a stator sheet of the stator, to form a flow space for a fluid in such a way that stator windings of the stator can be flowed around by the fluid that can be introduced into the flow space through at least one fluid supply opening.

[0002] Electrical machines with high power density are subject to high thermal stress during operation. To sufficiently reduce component temperatures, direct liquid cooling can be used. Various elements, such as a rotor core, a stator core, magnets, and / or windings, can be cooled through direct contact with a suitable coolant. Various oils, for example, are suitable for this purpose.

[0003] Regardless of the specific design of an electrical machine, the stator and rotor are usually arranged concentrically, with an air gap between the rotor and stator. If direct liquid cooling is used for cooling, the liquid coolant can also penetrate the narrow gap between the rotor and stator. The resulting frictional losses during rotor rotation can then lead to power losses.

[0004] Against this background, it is an object of the invention to improve cooling for a stator or stator lamination of an electrical machine. In particular, a guide for a fluid or cooling medium is to be improved in order to enable improved heat transfer.

[0005] This object is achieved by an electrical machine having the features of claim 1. The dependent claims relate to advantageous developments of the invention.

[0006] According to a first aspect, an electrical machine is specified, comprising a stator and a fluid line device, wherein the fluid line device has at least one fluid supply opening arranged axially spaced from a stator sheet of the stator and is configured, together with a stator sheet of the stator, to form a flow space for a fluid such that stator windings of the stator can be flowed around by the fluid that can be introduced into the flow space through the at least one fluid supply opening.

[0007] The stator windings are typically wound around teeth of the stator lamination and can be provided in the form of a concentrated winding or a distributed winding. On the end faces of the stator lamination, the stator windings form winding overhangs, which are arranged in particular outside the stator lamination core. Because the fluid is or can be introduced into the flow chamber at an axial distance from the stator lamination, i.e. in a region of the winding overhangs of the stator windings, fresh fluid can flow around the winding overhangs, which can promote heat transfer between the winding overhangs and the fluid. In addition, a continuous mixing of the fluid present in the flow chamber is possible, in particular in the region of the winding overhangs, which in turn can promote heat dissipation.

[0008] An electric machine can be used, for example, as an electric traction machine for an electrically powered motor vehicle. The electric machine is designed, in particular, as a current-excited asynchronous machine (ASM), a synchronous machine (SSM), or a permanent-magnet synchronous machine (PSM). The electric machine has a stationary stator with a stator lamination and a rotor that is mounted so as to be movable, in particular rotatable, relative to the stator. The stator lamination is designed, in particular, as a stator lamination stack made of axially stacked laminations. In addition, the stator lamination has at least one electrically conductive winding or stator winding, which is designed to generate or excite a magnetic flux by conducting current.

[0009] The fluid can, for example, be a coolant, in particular an electrically non-conductive one, which is taken from a coolant circuit or a lubricant circuit and is or can be introduced into the flow chamber via the at least one fluid supply opening in order to flow there. The flow chamber is in particular formed between the stator lamination and the fluid conduction device or is delimited by the latter. This allows flow to be guided along the stator windings without fluid being able to enter an interior space of the electrical machine. In particular, the fluid has a high thermal conductivity, so that a temperature distribution in the stator windings and / or the stator lamination can be homogenized and / or local hot spots can be avoided.

[0010] The fluid line device is provided as a separate, in particular multi-part component, which is designed to match the geometry of the stator or the stator lamination and its windings or winding heads in order to provide a flow space with a fluid line routing favorable for heat dissipation. For this purpose, the fluid line device has at least one fluid supply opening, which can be provided, in particular, on the circumference of the fluid line device. In this case, several fluid supply openings, in particular evenly spaced from one another, can be provided to enable uniform flow around all winding heads.

[0011] The invention is based, among other things, on the idea of ​​using a coolant sleeve to conduct a fluid in such a way that it can first flow around winding overhangs, which typically represent a hot spot on the stator, and finally flow along the stator windings to enable cooling of the stator. This enables heat transfer and removal. In addition, the proposed solution can be used to form a flow chamber by means of the fluid conduction device, which is fluid-tight with respect to an interior of the electrical machine or an air gap between the stator and rotor of the electrical machine. Due to the thermal connection between the stator windings and the fluid created by the fluid flowing between the stator lamination and the fluid conduction device, heat generated during operation can be dissipated and removed from the system.By means of the fluid guidance device, the fluid can be guided or directed along part or the entire axial extent of the stator lamination or the stator windings, thus homogenizing the temperature distribution and / or avoiding local hot spots. This can, for example, increase the efficiency and / or continuous power of the electric machine. The proposed electric machine can provide a cost-, space-, and / or production-time-optimized solution for cooling a stator or a stator lamination.

[0012] In one embodiment, the winding overhangs of the stator windings are enclosed by the flow chamber formed by the fluid-conducting device on both end faces of the stator lamination. This allows a flow chamber to be formed that completely surrounds the stator windings, wherein the flow chamber is fluid-tight with respect to an interior of the electric machine or the air gap between the stator and rotor by means of the fluid-conducting device. This allows, on the one hand, a cooling effect to be achieved at both end-face winding overhang regions, and, on the other hand, the penetration of cooling fluid into the air gap and / or the resulting friction and / or power losses to be reduced.

[0013] In one embodiment, the fluid conduction device has at least one cap region which is designed to encompass winding heads of the stator windings on one end face of the stator lamination. The cap region is arranged in particular on the end face of the stator lamination in order to form a partial flow space for the winding heads in order to be able to achieve the most favorable and / or complete flow around the winding heads. The at least one fluid supply opening can in particular be provided in a circumferential region in the cap region so that fluid can be supplied via a housing of the stator and / or the electric machine through the fluid supply openings in an improved manner. As a result, a fluid entering the flow space or partial flow space can be quickly transported to the winding heads or flow around them in order to enable heat to be dissipated at the winding heads. From this cap region orThe fluid can then flow into the area of ​​the stator lamination through the partial flow space formed by the cap area, in particular via stator or winding slots, in order to cool the stator windings there.

[0014] In one embodiment, the cap region has at least one mounting element and at least one cover element, which together can form the cap region. The mounting element and / or the cover element can be designed to be rotationally symmetrical in order to be arranged on an end face of the typically hollow-cylindrical stator lamination and to be able to encompass the winding heads. In this case, the mounting element can be designed, in particular, to be fastened to the end face of the stator lamination in order to enable the cap region and / or the fluid conduction device to be installed as simply as possible. The cover element is designed, in particular, to form a or the partial flow space around the winding heads of the stator windings on a respective end face of the stator lamination. In this case, the cover element can be designed to interact or cooperate with the mounting element on the circumferential side in such a way thatTo form a positive and / or non-positive connection in such a way that a sealing effect can be achieved with respect to the flow chamber relative to the interior of the electrical machine. At least one sealing device can be provided at the connection point(s) between the mounting element and the cover element. The multi-part assembly thus enabled can reduce the susceptibility to errors, while still allowing for a low weight of the individual components.

[0015] In one embodiment, the fluid conduction device has a sleeve element arranged on an inner circumference of the stator lamination. For example, the sleeve element can be arranged on the stator lamination by means of an injection molding process. The sleeve element is in particular designed to engage with the cap region or the cover element on both of its end faces and to form a fluid-tight connection there in each case, such that the flow space of the fluid conduction device is fluid-tight with respect to the interior of the electrical machine. Because the sleeve element is arranged in the air gap between the stator and the rotor of the electrical machine, penetration of fluid into the air gap can be better prevented.In addition, the sleeve element can be designed in such a way that magnetic and / or dynamic properties of the electrical machine are not influenced or are influenced only to a small extent by the sleeve element.

[0016] In one embodiment, the electric machine has a housing, and the housing has at least one fluid opening, by means of which the fluid can be conducted into the fluid line device. In this case, the housing of the electric machine can simultaneously form a housing for the stator. The position of the at least one fluid opening is designed, in particular, to correspond to the position of the at least one fluid supply opening in the fluid line device, so that fluid can be guided, in particular directly, from one fluid opening to a fluid supply opening. This makes it possible to omit additional line elements and / or channels, which can further simplify assembly.

[0017] In one embodiment, the fluid opening is arranged axially spaced from the stator lamination of the stator in the housing. This axial spacing of the fluid opening from the stator lamination allows for a correspondence between the fluid opening and the fluid supply opening of the fluid line device, thus enabling the most direct supply of coolant into the flow space possible.

[0018] In one embodiment, the fluid supply opening and / or the fluid opening has a flow element. The flow element can, for example, be configured to cause turbulence in the fluid or coolant. This can generate a swirling flow when the fluid enters the flow space, which can form around the winding heads and in particular according to an inner contour of the fluid conduction device or the cap region and / or the mounting and / or cover element. The mixing of the fluid flow at the winding heads that can be achieved in this way can lead, in particular locally, to higher flow velocities of the fluid, whereby improved heat dissipation can be achieved. In addition, the effects of boundary layer separation of the fluid flow can be reduced and any local hotspots that may arise as a result can be avoided.

[0019] In one embodiment, the fluid can be conducted from at least one first fluid supply opening on a first end face of the stator to at least one second, oppositely arranged end face of the stator and can be discharged from the flow chamber via at least one fluid discharge opening on the second end face of the stator. This allows a flow direction for the fluid to be defined, namely from the fluid supply opening(s) to the fluid discharge opening(s). This allows for uniform flow in one flow direction to enable continuous heat dissipation by means of the fluid in the flow chamber.

[0020] In one embodiment, the fluid can be introduced into the flow chamber from at least one fluid supply opening on each end face of the stator and can be discharged from the flow chamber via at least one fluid discharge opening located substantially in the axial center of the flow chamber. This allows fluid to be supplied to both end faces of the stator lamination, thereby achieving a uniform cooling effect for the winding heads of the stator windings at both ends.

[0021] Further advantages and possible applications of the invention will become apparent from the following description in conjunction with the figures. Fig. 1 shows a schematic representation of a first embodiment of an electrical machine according to the invention. Fig. 2 shows a schematic representation of a second embodiment of an electrical machine according to the invention. Fig. 3 shows a schematic detailed representation of a front area of ​​the first embodiment of an electrical machine according to the invention. Fig. 4 shows a schematic detailed representation of a front area of ​​a third embodiment of an electrical machine according to the invention. Fig. 5 shows a schematic sectional view of the front area of ​​the third embodiment of an electrical machine according to the invention.

[0022] Fig. 1 shows an electrical machine 10 according to the invention according to a first exemplary embodiment in a schematic sectional view along an axis of rotation of the electrical machine 10.

[0023] The electric machine 10 has a stator 11 with a stator lamination 21 and a rotor 12 rotatably mounted relative to the stator 11, wherein an air gap 13 is formed between the stator 11 and the rotor 12.

[0024] Furthermore, the electric machine 10 has a fluid line device 20 which, together with the stator lamination 21 of the stator 11, forms a flow chamber 22 for a fluid F. The fluid line device 20 has at least one fluid supply opening 23 arranged axially spaced from the stator lamination 21. This at least one fluid supply opening 23 is in particular assigned to a fluid opening 15 arranged in a housing 14 of the electric machine 10, so that the fluid F can be introduced into the flow chamber 22 through the fluid opening 15 and the fluid supply opening 23.

[0025] The flow chamber 22 surrounds stator windings 24 on both end faces of the stator 11 in a fluid-tight manner, so that the stator windings 24 and their winding heads 25 can be flowed around by the fluid F that can be introduced into the flow chamber 22 through the at least one fluid supply opening 23. As a result, the fluid F provided for cooling can be introduced, in particular, directly into a region of the winding heads 25 of the stator windings 24 in order to enable mixing of the flow chamber 22 with fresh fluid F or coolant.

[0026] The fluid line device 22 has a cap region 26 at each of its front or axial ends, which is designed to encompass the winding heads 25 of the stator windings 24 of one end face of the stator lamination 21 and to form a (partial) flow chamber. The cap region 26 has a circumferentially formed mounting element 27 and a circumferentially formed cover element 28, which together form the cap region 26. In addition, the fluid line device 22 has a sleeve element 29 arranged on an inner circumference of the stator lamination 21. Through the interaction of the stator lamination 21, mounting element 27, cover element 28 and sleeve element 29, a fluid-tight flow chamber 22 can be formed. This structure will be described below in connection with Fig. 3 described in more detail.

[0027] In the illustrated embodiment, the fluid F can be introduced into the flow chamber 22 from at least one fluid supply opening 25 on each end face of the stator 11 and can be discharged by means of at least one fluid discharge opening 223, which is arranged substantially in an axial center of the flow chamber 22. The fluid discharge opening 223 can be formed by means of a channel in the stator lamination 21, and a corresponding fluid opening 15 can be provided in the housing 14 to discharge the fluid F from the electrical machine 10. This allows fluid to be supplied from both sides, thus enabling fluid mixing for both end-face winding head regions and thus an improved cooling effect.

[0028] In Fig. 2 shows a second exemplary embodiment of an electrical machine 10 according to the invention in a schematic sectional view along a rotational axis of the electrical machine 10. The electrical machine 10 of this exemplary embodiment largely corresponds to the Fig. 1, with the difference that a different flow configuration is provided for the fluid F.

[0029] In the illustrated embodiment, the fluid F can be conducted from at least one first fluid supply opening 23 on a first end face of the stator 11 to at least one second, oppositely arranged end face of the stator 11 and can be discharged from the flow chamber 22 via at least one fluid discharge opening 223 on the second end face of the stator 11. As a result, the fluid flow can flow essentially in an axial direction along the stator windings 24 to cool them.

[0030] Fig. 3 shows a schematic detailed representation of a frontal area of ​​the first embodiment of an electrical machine 10 according to the invention from Fig. 1.

[0031] In the present embodiment, the cap region 26 of the fluid line device 20 is formed by the mounting element 27 and the cover element 28. The mounting element 27 is attached to the stator sheet 12 at the end face by means of at least one screw.

[0032] The mounting element 27, like the cover element 28, is essentially annular in shape in order to be arranged on the end face of the stator lamination 21 and, together with the sleeve element 29, which is arranged on an inner circumference of the stator lamination 21, to form the fluid conduction device 20 or the flow chamber 22. For this purpose, the mounting element 27 is designed to engage with the cover element 28 in such a way as to form a fluid-tight connection. At its inner edge region, the cover element 28 is designed to engage with the sleeve element 29 in such a way as to also form a fluid-tight connection. In particular, the cover element 28 is designed to be connected to the mounting element 27 and / or the sleeve element 29 in an assembly process by means of a positive and / or non-positive connection.

[0033] Fig. 4 shows a schematic detailed representation of a frontal area of ​​a third embodiment of an electrical machine 10 according to the invention. The electrical machine 10 of this embodiment largely corresponds to the one shown in Fig. 1, with the difference that the fluid supply opening 23 has a flow element 30.

[0034] The flow element 30 is arranged in the fluid supply opening 23 and configured to generate a swirling flow in the fluid F. This can cause turbulence in the fluid F in the flow chamber 22, which can continue according to an inner contour of the fluid conduit device 20 and / or the mounting element 27 and / or the cover element 28. This allows higher flow velocities for the fluid F to be achieved locally and / or particularly at the winding heads 25, which can result in better heat dissipation.

[0035] As shown, the fluid F can thereby reach all areas of the flow space 22 in particular in order to avoid dead water areas and / or local hotspots.

[0036] Fig. 5 shows a schematic sectional view along the section AA of the frontal area of ​​the third embodiment of the electrical machine 10 according to the invention from Fig. 4.

[0037] In the present illustration, it can be seen that by means of the flow element 30 arranged in the fluid supply opening 23 of the fluid line device 20, turbulences can be generated in the fluid flow F in the flow space 22 in order to achieve an improved flow around the winding heads 24 and thus to improve heat dissipation. LIST OF REFERENCE SYMBOLS 10 Electric machine 11 Stator 12 Rotor 13 Air gap 14 housings 15 Fluid opening 20 Fluid line device 21 Stator sheet 22 Flow space 23 Fluid supply opening 24 stator windings 25 winding heads 26 Cap area 27 Mounting element 28 Cover element 29 Sleeve element 30 flow element F Fluid

Claims

[1] Electrical machine (10) comprising a stator (11) and a fluid line device (20), wherein the fluid line device (20) has at least one fluid supply opening (23) arranged axially spaced from a stator sheet (21) of the stator (11) and is designed, together with the stator sheet (21), to form a flow space (22) for a fluid (F) such that the fluid (F) which can be introduced into the flow space (22) through the at least one fluid supply opening (23) can flow around stator windings (24) of the stator (11). [2] Electrical machine (10) according to the preceding claim, wherein winding heads (25) of the stator windings (24) on both end faces of the stator lamination (21) are encompassed by the flow space (22) formed by means of the fluid conduction device (20). [3] Electrical machine (10) according to one of the preceding claims, wherein the fluid conduction device (20) has at least one cap region (26) which is designed to encompass winding heads (25) of the stator windings (25) of an end face of the stator lamination (21). [4] Electrical machine (10) according to the preceding claim, wherein the cap region (26) has at least one mounting element (27) and at least one cover element (28). [5] Electric machine (10) according to one of the preceding claims, wherein the fluid conduction device (20) comprises a sleeve element (29) arranged on an inner circumference of the stator lamination (21). [6] Electrical machine (10) according to one of the preceding claims, wherein the electrical machine (10) has a housing (14) and the housing (14) has at least one first fluid opening (15) by means of which the fluid (F) can be supplied to the flow space (22) of the fluid line device (20). [7] Electric machine (10) according to the preceding claim, wherein the fluid opening (15) is arranged axially spaced from the stator lamination (21) in the housing (14). [8] Electrical machine (10) according to the preceding claim, wherein the fluid supply opening (23) has a flow element (30). [9] Electrical machine (10) according to one of the preceding claims, wherein the fluid (F) can be conducted from at least one first fluid supply opening (23) on a first end face of the stator (11) to at least one second, oppositely arranged end face of the stator (11) and can be discharged from the flow space (22) via at least one fluid discharge opening (223) on the second end face of the stator (11). [10] Electrical machine (10) according to one of claims 1 to 8, wherein the fluid (F) can be introduced into the flow space (22) from at least one fluid supply opening (23) on both end faces of the stator (11) and can be discharged from the flow space (22) via at least one fluid discharge opening (23) which is arranged substantially in an axial center of the flow space (22).

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