Axial flux machine

Abstract

The invention relates to an axial flux machine with a hollow cylindrical stator (3) having axially open stator slots (9) in which a coil winding with radially inner and radially outer winding heads (15, 17) is inserted, wherein the stator (3) has a laminated core (20) wound from a strip of sheet metal, the layers of which are stacked radially on top of each other, and wherein a cooling channel arrangement is integrated into the stator laminated core (20) and is connected to a coolant circuit. According to the invention, the cooling channel arrangement integrated into the stator laminated core (20) has radially outer and / or radially inner coolant outlets (33, 35).

Description

[0001] The invention relates to an axial flux machine according to the preamble of claim 1 or 2.

[0002] In an axial flux machine, unlike a radial flux machine, the magnetic field runs parallel to the rotor's axis of rotation. The stator has stator slots evenly distributed around its circumference and open along its axis, into which a coil winding with radially inner and radially outer winding ends is inserted.

[0003] An axial flux machine is known from DE 10 2014 222 121 A1. Its stator comprises a stator lamination stack wound from a strip of sheet metal. The layers of this stack are radially stacked on top of each other in the wound state. A channel-like cavity is integrated into the stator lamination stack, which can be used to conduct or guide cooling fluid for cooling the stator.

[0004] The following situation, described in DE 10 2014 222 121 A1, leads to an impairment of the cooling performance provided by the cooling fluid: The cavity integrated in the stator lamination stack is sealed radially outwards and radially inwards by a sealing sheet layer. Furthermore, the cavity is not located directly in the area of ​​the stator slots or the winding heads, but rather axially spaced from them on the rear side of the lamination stack facing away from them.

[0005] From DE 10 2021 108 956 A1, a stator for an axial flux motor is known, comprising a stator lamination stack mounted on a flange. The stator lamination stack has a rear side that is positively and non-positively attached to a front side of the flange, and / or a cooling channel is formed between the stator lamination stack and the flange in the area of ​​attachment. The invention also relates to an axial flux motor with a rotor arranged between two stators, one or both of which are designed according to the invention. Further electric machines are known from DE 10 2014 222 121 A1, DE 33 34 501 A1, DE 10 2022 001 408 A1, and DE 10 2021 202 836 A1.

[0006] The object of the invention is to provide an axial flux machine with a cooling concept that enables increased cooling performance in a simple manner compared to the prior art.

[0007] The problem is solved by the features of claim 1 or 2. Preferred embodiments of the invention are disclosed in the dependent claims.

[0008] The invention relates to an axial flux machine with a hollow cylindrical stator featuring axially open stator slots. A coil winding with radially inner and radially outer winding heads is inserted in the stator slots. The stator comprises a stator core wound from a strip of laminations. In its wound state, the lamination layers are stacked radially on top of each other. A cooling channel arrangement, integrated into a coolant circuit, is also incorporated into the stator core. According to the invention, the cooling channel arrangement integrated into the stator core has radially outer and / or radially inner coolant outlets. A coolant flow exiting the respective coolant outlet can directly saturate the respective winding head. Therefore, in contrast to the prior art, the winding heads can be brought into direct cooling contact with the coolant, thus increasing the stator cooling capacity compared to the prior art.

[0009] The cooling channels can be introduced into the unwound sheet metal strip of the laminated core by a punching process or laser cutting. The cooling channels preferably run radially in close proximity to the windings. Gear oil can be used as a coolant. In the cooling channel arrangement according to the invention, each radial channel can be supplied by an axial channel. The axial channels lead to an annular distribution groove on the back of the laminated core.

[0010] To ensure sufficient strength of the sheet metal strip during winding, the axial channels must be geometrically adapted accordingly. For example, the channels can have an inclined profile or form an angle with the axis of rotation. This ensures that the weakening of the sheet metal strip is more homogeneous or distributed across several sections of the strip.

[0011] The radial channels can run between the winding slots or axially offset from them. This means that the radial channels can be located at the same axial level as the winding slots, overlap axially, and / or be positioned axially below them. One or more radial channels can be located next to a winding slot.

[0012] At the ends of the radial channels, i.e., at the coolant outlets, cross-sectional constrictions can be formed, resulting in a pronounced coolant jet that strikes and cools the winding heads. The cross-sectional constriction increases the flow velocity, while an increase in the channel cross-section causes a decrease in the coolant flow velocity. Alternatively, the coolant outlet can be designed as a spray nozzle, e.g., sponge-like or porous, to increase the exit area for the jet. This achieves the highest possible coverage or contact area with a radially outer and / or inner winding head. The axial channels can open centrally into the radial channels at a branching point to ensure a uniform pressure drop in both radial channels. The profile of the radial channels can take on various shapes. A rectangular profile with rounded corners is preferred.

[0013] Suitable manufacturing processes can create a rough surface in the radial channels for improved heat transfer (due to increased surface area); alternatively, a partially porous channel structure is also conceivable. To simplify manufacturing, the axial channels can be chamfered.

[0014] In the manufacturing process, the stator lamination is punched or laser-cut from the strip and then wound onto it. The predefined punching / laser cutting of the lamination allows for the creation of the complete geometry for the cooling channels. It is important to note that the cutouts in the lamination strip must not be too large, as this would result in insufficient strength for the winding process. This problem is particularly pronounced with the axial channels. To address this issue, the axial channels can be angled or arranged in a zigzag pattern. This increases the angle of the slope while ensuring that the axial channel still intersects the radial channels centrally at the branch point. Such an angled approach to the axial channels results in smaller cutouts in the lamination and thus higher strip strength during winding.

[0015] When designing radial channels, it's important to note that the cutout in the sheet metal strip can be slightly offset from one layer to the next. This results in a rough surface within the radial channels, which improves heat dissipation.

[0016] After the coolant exits the stator and saturates the winding heads, it drips down inside the electric motor housing. There, it must be collected and pumped out. It is advantageous to prevent coolant from entering the air gap of the electric motor. Plastic components can be used to act as splash guards for this purpose.

[0017] The winding head on the outside of the stator is larger than on the inside. Consequently, heat generation is also greater there. It may therefore be advantageous to have a higher coolant flow rate on the outside of the stator.

[0018] In one design variant, the radial channel can have a zigzag pattern in which the sheet metal cutouts are only slightly offset between the sheet layers. In the axial channel, the zigzag pattern can be significantly more pronounced to achieve uniform material weakening in the sheet metal strip.

[0019] The following are key aspects of the invention highlighted in detail: In a technical implementation, the cooling channel arrangement can have radial and axial channels. For optimal cooling performance, each stator tooth can be assigned at least one radially outer coolant outlet and / or one radially inner coolant outlet. By way of example, the cooling channel arrangement can have at least one axial channel extending axially from a coolant inlet to a branch point. At the branch point, the axial channel transitions into at least one radial channel. This radial channel extends to the radially inner coolant outlet and / or to the radially outer coolant outlet. Preferably, each stator tooth is assigned at least one such radial channel.

[0020] According to the invention, the channels and stator grooves are formed by the sheet metal strip having recesses which, in the wound state, at least partially overlap with adjacent sheet metal layers, thereby forming the channels and / or the stator grooves. The recesses are introduced into the sheet metal strip while it is still unwound, for example, by a punching process or laser cutting.

[0021] The lamination strip must possess sufficient strength for reliable winding into the stator lamination stack. Against this background, it is advantageous to adapt the axial channel's path accordingly to avoid excessive material weakening in the lamination strip. Preferably, therefore, the axial channel, in its wound state, does not extend completely along the entire stator lamination stack in axial alignment. Rather, according to the invention, the axial channel can have channel sections offset from one another by a radial offset. This allows the axial channel to run, at least partially, at an angle through a number of adjacent lamination layers. This results in smaller lamination gaps and thus higher lamination strip strength.

[0022] To further increase heat transfer between the stator lamination stack and the coolant, it is preferred if the coolant volume flow is guided through the radial or axial channels not in laminar, but rather in a pronounced turbulent flow.

[0023] Such pronounced turbulent flow can be achieved as follows: Each channel, especially each radial channel, in the stator lamination stack is at least partially bounded by the edges of cutouts in superimposed lamination layers. For turbulent coolant flow, it is advantageous if the edges of cutouts in adjacent lamination layers are slightly offset from each other perpendicular to the coolant flow direction. This increases the surface roughness on the inner wall of the channel.

[0024] Due to geometric constraints, the radially inner winding heads are smaller than the radially outer winding heads. Consequently, there is more winding head material on the radially outer side of the stator than on the radially inner side. Against this background, the flow parameters in the cooling channel arrangement, for example, the size of the channel cross-sections, can be adjusted so that the coolant flow rate directed radially outwards is larger than the coolant flow rate directed radially inwards.

[0025] Alternatively and / or additionally, the positioning of the branch point in the radial direction can be adjusted. For example, the branch point between the axial channel and the two radial channels can be located radially midway between the outermost and innermost coolant outlets. Furthermore, the two radial channels can be designed with identical channel geometries, and in particular, exhibit the same flow parameters throughout (i.e., cross-sectional area, surface roughness, etc.). This results in the same volumetric flow rate pressure drop in both radial channels.

[0026] In a technical implementation, the coolant inlet can be located on the rear side of the stator core axially opposite the stator slot side. For a structurally simple coolant circuit, the coolant inlet can be a distributor channel running in a ring around the stator axis. The respective axial channel can then be routed from this distributor channel towards the branch point.

[0027] The coolant circuit can include a coolant sump positioned below the stator in the vertical direction of the axial flux machine. Coolant dripping from the winding heads is collected in the coolant sump. From there, the coolant is circulated towards the coolant inlet.

[0028] The axial flux machine, in its assembled state, has a rotor that interacts with the stator. This rotor is axially separated from the stator by a free air gap. To supply the stator with coolant in a targeted manner, a coolant cover, typically annular in shape, is attached to the stator. The coolant cover largely seals the air gap and the rotor against the coolant applied to the stator winding ends. In this context, a fluid-tight or flow-tight seal does not necessarily mean a hermetic seal, i.e., a completely airtight seal. Rather, during operation of the electric machine, a slight coolant leakage through the sealing surfaces of the coolant cover into the rotor chamber may occur.

[0029] The coolant cover also serves a dual function: securing the coil winding laid in the stator slots. For this purpose, the coolant cover can have the following geometry: Each stator tooth has a recess in the coolant cover through which a corresponding stator tooth top surface projects axially. Circumferentially, adjacent recesses in the coolant cover are spaced apart by radial ribs. These radial ribs run within the stator slots and axially secure the coil winding within them. Each radial rib can be designed to be elastically compliant. In this case, the radial rib can be pressed against opposing slot walls of the respective stator slot, generating an elastically compliant restoring force.Alternatively and / or additionally, the radial web of the coolant cover can be held in the respective stator groove by a positive-locking connection. In this positive-locking connection, a detent contour (i.e., for example, a detent projection) of the radial web can engage with a counter contour formed on the groove side wall.

[0030] The annular coolant cover can also transition radially outwards into a hollow cylindrical outer circumferential wall. This can be brought into tight contact with the inside of the electric motor housing. Alternatively and / or additionally, the annular coolant cover can transition radially inwards into a sleeve-shaped hub section through which a rotor shaft can be guided. The sleeve-shaped hub section can extend through the inner circumference of the stator. The hollow cylindrical outer circumferential wall of the coolant cover can radially encircle the air gap and the rotor.

[0031] In addition to the stator lamination stack, the stator also features a stator body. This body has a U-shaped cross-section that is open in the axial direction. When assembled, the stator lamination stack can be glued into the U-shaped profile of the stator body with its rear side facing away from the stator groove. In this configuration, the distribution channel is an annular groove formed in the base of the stator body, which is covered by the rear side of the stator lamination stack. Alternatively, the distribution channel can also be machined directly into the rear side of the stator lamination stack as an annular groove.

[0032] Exemplary embodiments of the invention are described below with reference to the accompanying figures.

[0033] They show: Fig. 1 to 13 different views of an axial flux machine according to the invention.

[0034] In the Fig. Figure 1 shows a sectional view of an axial flux machine to the extent necessary for understanding the invention. Accordingly, the axial flux machine has an electric machine housing 1 in which a stator 3 and a rotor 5 (indicated by dashed lines) are inserted, spaced apart from each other axially by a free air gap 7. The stator 3 has, for example, according to the Fig. The stator has three circumferentially evenly distributed stator slots 9, spaced apart from each other by means of intermediate stator teeth 11. The stator slots 9 are open in the axial direction. A coil winding is laid in the stator slots 9. This winding consists of winding wires or conductors with straight conductor legs 13 ( Fig. 1) exhibiting, which run radially through the stator slots 9. The straight conductor legs 13 extend in the Fig. 1 into radially inner winding heads 15 and radially outer winding heads 17, each spanning a number of stator slots 9 in the circumferential direction. The stator 3 is also assigned an annular disc-shaped coolant cover 19 made of plastic, which largely seals the air gap 7 and the rotor 5 from a coolant 38 applied to the stator-side winding heads 15, 17 ( Fig. 5) Seal.

[0035] For example, from the Fig. As shown in Figures 2 to 5, the stator 1 has a stator lamination stack 20 in which a cooling channel arrangement consisting of radial channels 21 and axial channels 23 is integrated. The axial and radial channels 21, 23, as well as the stator slots 9, are formed by creating recesses in the unwound lamination strip. These recesses overlap at least partially in adjacent lamination layers in the wound lamination stack 20, thus forming the channels 21, 23, and the stator slots 9. For clarity, the lamination strip is shown with an exaggerated thickness in the figures. In reality, the thickness is, for example, less than 0.5 mm.

[0036] The radial and axial channels 21, 23 are components of a coolant circuit located in the Fig. 5 is indicated. According to the Fig. 5 The stator 1 is constructed in two parts, consisting of the stator lamination stack 20 and a stator base body 25. The stator base body 25 has a U-profile in cross-section that is open in the axial direction, into which the stator lamination stack 20 is glued with its rear side 27 facing away from the stator slot. In the base of the stator base body 25, the Fig. 5 a ring groove is formed, which is covered by the rear side 27 of the lamination stack. The ring groove forms a distribution channel 29, from which in the Fig. 5 an axial channel 23 extends to a branch point 31. At the branch point 31, the axial channel 23 transitions into two radial channels 21, which open to the outside at a radially inner coolant outlet 33 and a radially outer coolant outlet 35. According to the Fig. 2 to 5, each of the stator teeth 11 is assigned such a cooling channel arrangement (consisting of radial and axial channels 21, 23). During operation of the axial flux machine, a coolant flow is guided through the cooling channel arrangement and discharged at the coolant outlets 33, 35. The discharged coolant flow permeates the respective winding head 15, 17, thereby bringing it into direct cooling contact with the coolant 38 ( Fig. 5) come.

[0037] In the Fig. 5. In the stator base body 25, axially on both sides of the distributor channel 29, suitable sealing grooves 26 for gaskets are provided. The sealing grooves 26 are dimensioned such that the gaskets are completely recessed in the respective sealing groove 26 when the stator lamination stack 20 is glued in place, in order to provide a perfect bonding surface between the back of the lamination stack 27 and the stator base body 25. The gaskets prevent any adhesive from penetrating the cooling channel assembly.

[0038] In the Fig. The coolant circuit also includes a coolant sump 37, which is located below the stator 3. The coolant 38 dripping from the winding heads 15, 17 is collected in the coolant sump 37 and circulated towards the distribution channel 29 by pumps 39, 41.

[0039] In the Fig. 4 or Fig. The branch point 31 is located centrally between the radially inner coolant outlet 33 and the radially outer coolant outlet 35. The two radial channels 21 are identically designed, resulting in an identical volume flow pressure drop in both radial channels 21 during coolant supply.

[0040] As from the Fig. 4 or Fig. As can be seen further in Figure 5, the axial channel 23 does not extend completely continuously in axial alignment through the stator lamination stack 20. Rather, the axial channel 23 has a total of three channel sections 43, 44, 45, which (viewed in the radial direction) are offset by a radial offset Δr ( Fig. 4) are offset from each other. This results in the axial channel 23 running partially obliquely through a number of adjacent sheet metal layers, leading to smaller sheet metal cutouts and thus to higher sheet metal strip strength. In the Fig. 4 or Fig. 5 the two channel sections 43, 45 are arranged in axial alignment to each other, while the middle channel section 44 is offset by the radial offset Δr to the other two channel sections 43, 45.

[0041] The geometry and function of the coolant cover 19 are described below. Fig. 1, Fig. 2, as well as 12 and 13, are described: As can be seen from the Fig. 2 or Fig. As can be seen from Figure 13, the coolant cover 19 has a recess for each stator tooth 11 through which a stator tooth top surface projects in the axial direction. The circumferentially adjacent recesses of the coolant cover 19 are each spaced apart from one another by a radial web 57. In the Fig. In the assembly state shown in Figure 2, each of the radial webs 57 runs within the respective stator slots 9 to secure the coil winding axially in the stator slots 9.

[0042] To ensure that the radial web 57 of the coolant cover 19 is reliably held in its axial position, the following measures have been taken: First, the radial web 57 is designed to be elastically compliant, so that it is pressed against opposing groove side walls of the respective stator groove 9, generating an elastically compliant restoring force. For this purpose, the radial web 57 is designed to be elastically compliant, so that it is pressed against opposing groove side walls of the respective stator groove 9. Fig. 13 Each radial web 57 has a material weakening 58 in its center. When the radial web 57 is inserted into the stator groove 9, the material weakening 58 allows for elastically compliant radial web deformation in the transverse direction of the radial web.

[0043] Secondly, each of the radial webs 57 of the coolant cover 19 is held in the respective stator groove 9 by a positive-locking connection. The positive-locking connection is in the Fig. 12 and Fig. 13 implemented as a clip connection, in which a web-side detent projection 60 ( Fig. 13) into a corresponding counter contour 62 ( Fig. 12) can snap into place on the top of the stator slot.

[0044] The ring-shaped coolant cover 19 further features, according to the Fig. 1 or Fig. In cross-section 2, a hollow cylindrical outer circumferential wall 51 is radially external, which can be brought into sealing contact with the inside of the electric motor housing 1. Furthermore, the annular coolant cover 19 transitions radially internally into a sleeve-shaped hub section 53, through which the rotor shaft 55 extends. The sleeve-shaped hub section 53 is arranged – in radial alignment – ​​between the coil winding and the radially inner rotor shaft 55. In contrast, the hollow cylindrical outer circumferential wall 51 of the coolant cover 19 radially encircles the air gap 7 and the rotor 5.

[0045] As in the Fig. As shown in Figure 6, the opening edges 47 of sheet metal recesses in the stacked sheet metal layers of the stator sheet metal package 20 form the two radial channels 21 branching off from the junction 31. In the Fig. In the embodiment shown in 6, the two radial channels 21 do not have a smooth inner wall; rather, in the Fig. 6 The opening edges 47 of the sheet metal recesses are positioned slightly offset from each other by offset dimensions Δx. This increases the surface roughness in the two radial channels 23. A pronounced turbulent flow pattern therefore forms in the flowing coolant volume flow, which increases the heat transfer from the stator sheet metal stack 20 to the coolant 38.

[0046] In the Fig. 7 is a - compared to the Fig. 4 or Fig. 5 - Alternative routing of the axial channel 23 in the stator lamination stack 20 is shown. Accordingly, the axial channel 23 is again divided into three channel sections 43, 44, 45.

[0047] These are offset in a step-like or staircase-like manner by radial offsets Δr, starting from a radially centrally arranged channel section 43, which opens into the branching point 31, up to a radially outer channel section 45, which leads into the (in the Fig. 7 (not shown) distribution channel 29 empties into it.

[0048] In the Fig. Figures 8 to 10 show different design variants of the stator lamination stack 20 in side views. According to the Fig. 8 Each of the radially outer coolant outlets 35 is implemented as an elongated hole, the longitudinal extent of which corresponds approximately to the slot height of the stator slots 9. In contrast, in the Fig. 9 a total of two radially outer coolant outlets 35 per stator tooth 11 are provided. In the Fig. In contrast, the stator teeth 11 are free of radially external coolant leakage 35. Rather, in the Fig. 10 the radially outer coolant outlet 35 is positioned offset by an axial distance a to the stator slot bottom 49.

[0049] In the Fig. Figure 11 shows a stator lamination stack 20 according to a further embodiment. Accordingly, the stator lamination stack 20 has – analogous to the Fig. 5 - in each stator tooth 11, there is one radially outer and one radially inner coolant outlet 33, 35. In contrast to the Fig. 5 is in the Fig. 11 the distributor channel 29 is incorporated as an annular groove directly into the back of the stator stator stator stack 20. Reference symbol list 1 Electric machine housing 3 Stator 5 Rotor 7 air gap 9 Stator slot 11 Stator tooth 13 straight ladder leg 15, 17 winding heads 19 Coolant cover 20 stator sheet metal package 21 Radial canal 23 Axial canal 25 Stator base bodies 26 Sealing groove 27 Sheet metal package back 29 Distribution channel 31 Junction 33, 35 Canal outlets 37 Coolant sump 38 Coolant 39, 41 Pumps 43, 44, 45 canal sections 47 Opening edge 49 Stator slot bottom 51 Outer perimeter wall 53 sleeve-shaped hub section 55 Rotor shaft 57 Radial web 58 Material weakening 60 Rastvorsprung 62 Counter contour Δr radial offset Δx offset dimension a axial distance

Claims

[1] Axial flux machine with a hollow cylindrical stator (3) with axially open stator slots (9) in which a coil winding with radially inner and radially outer winding heads (15, 17) is inserted, wherein the stator (3) has a laminated core (20) wound from a sheet metal strip, the sheet metal layers of which are radially stacked one above the other, and wherein a cooling channel arrangement is integrated in the stator laminated core (20), which is integrated in a coolant circuit, wherein the cooling channel arrangement integrated in the stator laminated core (20) has radially outer and / or radially inner coolant outlets (33, 35), so that a coolant volume flow emerging from the coolant outlet (33, 35) saturates the respective winding head (15, 17), characterized bythat the stator (3) has a stator base body (25) which has a U-profile that is open in the axial direction in cross-section, that the stator laminated core (20) can be inserted into the U-profile of the stator base body (25) with its rear side facing away from the stator groove side, and that an annular, circumferential distribution channel (29) forming a coolant inlet point is an annular groove formed in the profile base of the stator base body (25) that is covered by the laminated core rear side (27), or that alternatively the distribution channel (29) has an annular groove machined directly into the laminated core rear side (27). [2] Axial flux machine with a hollow cylindrical stator (3) with axially open stator slots (9) in which a coil winding with radially inner and radially outer winding heads (15, 17) is inserted, wherein the stator (3) has a laminated core (20) wound from a sheet metal strip, the laminated core layers of which are radially stacked one above the other, and wherein a cooling channel arrangement is integrated in the stator laminated core (20), which is integrated in a coolant circuit, wherein the cooling channel arrangement integrated in the stator laminated core (20) has radially outer and / or radially inner coolant outlets (33, 35) so that a coolant volume flow emerging from the coolant outlet (33, 35) saturates the respective winding head (15, 17), wherein the axial flux machine has a rotor (5) which interacts with the stator (3) and which is axially displaceable via an air gap (7). is spaced from the stator (3), characterized bythat the stator (3) is assigned an annular disc-shaped coolant cover (19) which seals the air gap (7) and the rotor (5) in a largely fluid-tight manner with respect to the coolant (38), that the coolant cover (19) has a recess for each stator tooth (11) through which a stator tooth upper side projects in the axial direction, that circumferentially adjacent recesses of the coolant cover (19) are spaced from one another by a radial web (57), and that the radial web (57) of the coolant cover (19) secures the coil winding axially in the stator slots (9). [3] Axial flow machine according to claim 1 or 2, characterized by that each stator tooth (11) is assigned at least one radially outer coolant outlet (35) and / or one radially inner coolant outlet (33). [4] Axial flow machine according to claim 1, 2 or 3, characterized bythat the cooling channel arrangement has radial channels (21) and axial channels (23), and / or that in particular the cooling channel arrangement has at least one axial channel (23) which extends in the axial direction from a coolant inlet point (29) to a branching point (31) in which the axial channel (23) merges into at least one radial channel (21) which runs as far as the radially inner coolant outlet (33) and / or as far as the radially outer coolant outlet (35), and / or that at least one radial channel (21) runs in each stator tooth (11). [5] Axial flow machine according to one of the preceding claims, characterized by in that the channels (21, 23) and the stator slots (9) are formed in that the sheet metal strip has recesses which, in the wound state, at least partially overlap in adjacent sheet metal layers, specifically to form the channels (21, 23) and / or the stator slots (9). [6] Axial flow machine according to one of claims 4 or 5, characterized by that the axial channel (23) does not extend completely continuously in axial alignment through the stator laminated core (20), but has channel sections (43, 44, 45) which are offset from one another by a radial offset (Δr), which in particular leads to smaller sheet metal recesses and thus to a higher sheet metal strip strength. [7] Axial flow machine according to one of the preceding claims, characterized by that each channel (21, 23), in particular radial channel (21), in the stator laminated core (20) is at least partially delimited by opening edges (47) of sheet metal recesses of superimposed sheet metal layers, and that the opening edges (47) of adjacent sheet metal layers are slightly offset from one another transversely to the coolant flow direction by an offset dimension (Δx) in order to generate a turbulent flow pattern in the coolant flow. [8] Axial flow machine according to one of the preceding claims, characterized bythat due to geometric conditions, the radially inner winding heads (15) are smaller than the radially outer winding heads (17), and that in particular by adapting flow parameters, such as the size of channel flow cross sections, the coolant volume flow directed radially outwards can be designed to be larger than the coolant volume flow directed radially inwards. [9] Axial flow machine according to one of claims 4 to 8, characterized by that the branching point (31) between the axial channel (23) and the two radial channels (21) is arranged centrally in the radial direction between the radially outer coolant outlet (35) and the radially inner coolant outlet (33), and / or that the two radial channels (21) have identical channel geometries, ie in particular have the same flow cross-section throughout, whereby in particular the same volume flow pressure drop prevails in both radial channels (21). [10] Axial flow machine according to one of claims 4 to 9, characterized by that the coolant inlet point (29) is arranged on the rear side (27) of the laminated core opposite the stator slot side. [11] Axial flow machine according to one of the preceding claims, characterized by that the axial flow machine has a coolant sump (37) in which the coolant (38) dripping from the winding heads (15, 17) collects, and that in particular the coolant (38) can be circulated from the coolant sump (37) in the direction of the coolant inlet point (29). [12] Axial flow machine according to claim 1, characterized by that the radial web (57) of the coolant cover (19) is designed to be elastically flexible to secure its position, so that the radial web (57) is pressed against opposing groove side walls of the respective stator groove (9) while building up an elastically flexible restoring force. [13] Axial flow machine according to claim 12, characterized bythat the radial web (57) of the coolant cover (19) is held in the respective stator groove (9) via a positive connection, in which in particular a locking contour (60) of the radial web (57) can be brought into engagement with a counter-contour (62) formed on the groove side wall. [14] Axial flow machine according to one of claims 1, 12 or 13, characterized by that the coolant cover (19) merges radially outward into a hollow cylindrical outer circumferential wall (51) which can be brought into sealing contact with the inside of an axial flow machine housing (1), and / or that in particular the coolant cover (19) merges radially inward into a sleeve-shaped hub section (53) which is guided through the stator inner circumference, and / or that the hollow cylindrical outer circumferential wall (51) of the coolant cover (19) surrounds the air gap (7) and the rotor (5) radially outward.

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