Coolant supply system for an electrified axle power device

Abstract

The invention relates to a coolant supply system for an electrified axle drive having an electric machine, in the electric machine housing (1) of which a stator (4) cooperates with a rotor (5) which is spaced apart from the stator (4) by an air gap (85), wherein an electric machine interior for rotor interior cooling and / or for stator cooling is charged with coolant. According to the invention, the coolant supply system has a flow unit (64) by means of which an air flow (L) (L) can be generated which flows through the air gap (85) in the axial direction, as a result of which the air gap (85) is kept substantially free of coolant in order to reduce rotor drag losses.

Description

TECHNICAL FIELD

[0001] The invention relates to a coolant supply system for an electrified axle drive, according to the preamble of claim 1. BACKGROUND

[0002] Such an axle drive can have a wet-running electric machine in which the stator, in particular the winding heads of the stator winding, and the rotor are actively cooled with coolant, that is to say with oil. The rotor is spaced apart from the stator by an air gap. The interior space of the electric machine can be loaded with coolant for rotor interior cooling and / or for stator cooling.

[0003] It has been shown that coolant-containing air in the air gap between the rotor and the stator leads to a drag loss / drag power in the rotor, thereby reducing the efficiency of the electric machine.

[0004] Against this background, in an electric machine of this kind according to US 2021 / 0083555 A1, a compressed air line is integrated in the rotor and / or in the stator, which is in flow connection with the air gap. An air flow is generated in the axial direction through the air gap for a compressed air source. In this way, the air gap is kept substantially free of coolant, whereby the rotor drag loss can be reduced.

[0005] In US 2021 / 0083555 A1, the compressed air line runs within the stator and / or the rotor. The component geometry of the stator and / or the rotor is therefore distinguished from the conventional rotor / stator component geometry in a manner which is complex in terms of manufacturing technology.

[0006] Further electric machines are known from EP 3 193 434 B1 and EP 3 032 709 A1. A generator for a motor vehicle is known from US 2005 / 023909 A1. WO 2019 / 008220 A1 discloses an electric machine. A high speed generator venting arrangement for an air gap is known from US 4 496 862 A. GB 164 114 A discloses improvements at a dynamo electric machine. A cooling device for an electric machine is known from US 3 240 967 A. SUMMARY

[0007] It is an object of the present invention to provide a coolant supply system for an electrified axle drive in which the electric machine can be operated with higher efficiency in a simple manner compared to the prior art.

[0008] This object is achieved by the features of claim 1. Preferred refinements of the invention are disclosed in the dependent claims.

[0009] According to the application, a coolant supply system for an electrical machine is provided, in which, in an electrical machine housing, a stator cooperates with a rotor, which is spaced apart from the stator by an air gap. The electrical machine is embodied as a wet-running, coolant-through electrical machine, in which an electrical machine interior is loaded with coolant for rotor interior cooling and / or for stator cooling. Furthermore, the coolant supply system has a flow unit, by means of which an air flow can be generated. The air flow flows through the air gap in the axial direction. In this way, the air gap is kept substantially free of coolant-containing air, whereby rotor drag losses can be reduced. According to the feature part of claim 1, the rotor / stator arrangement has, on both sides in the axial direction, an air flow chamber, respectively, namely a rotor chamber in the specific embodiment. These two air flow chambers are in flow connection with the air gap arranged between them. According to the application, the air flow chambers, respectively, the rotor chambers, are divided into an air inlet-side air flow chamber and an air outlet-side air flow chamber. The air flow generated by the flow unit flows through the air inlet into the air inlet-side air flow chamber. A further flow path of the air flow is guided through the air gap into the outlet-side air flow chamber. From there, the air flow is discharged through the air outlet from the outlet-side air flow chamber.

[0010] In this way, according to the application, no geometric adaptations of the rotor and / or the stator are necessary in order to achieve the air flow through the air gap. Rather, according to the application, it is possible to simply make use of the conventional component geometry of the rotor or the stator in terms of manufacturing technology.

[0011] In one technical embodiment, the two air flow chambers, the air gap and the flow unit can be embedded in a closed air circuit. In this air circuit, the air flow generated by the flow unit flows through the air inlet into the inlet-side air flow chamber. From there, the air flow is guided in the axial direction through the air gap to the outlet-side air flow chamber. Furthermore, the air flow is guided back from the outlet-side air flow chamber through the air outlet to the flow unit.

[0012] In the electrical machine housing, the stator rotor arrangement has, on both sides in the axial direction, end-side, free housing chambers. The air flow chambers according to the application are integral parts of these housing chambers. Preferably, each of the two end-side housing chambers is divided by a coolant separation into a radially outer winding head chamber and a radially inner rotor chamber, which is largely fluidically separated therefrom, in which the rotor is arranged. Conversely, the stator together with the stator winding is positioned in the radially outer winding head chamber. In this way, the stator, which heats up particularly strongly in the electrical machine operation, can be supplied with coolant more specifically. Furthermore, the coolant supply of the winding head chamber is largely separated from the rotor chamber. In particular, the winding head of the stator can preferably be completely circulated by coolant. In this case, the winding head chamber can be substantially completely filled with coolant.

[0013] In the case of the above-mentioned division of the respective housing cavity into a radially outer winding head cavity and a radially inner rotor cavity, in particular the radially inner rotor cavity forms the air flow cavity according to the application. In this case, in particular the radially inner rotor cavity of the electric machine is embedded in the air circuit. In this context, the air inlet opens into the rotor cavity on the inlet side, while the air outlet opens into the rotor cavity on the outlet side.

[0014] In the case of the above-mentioned division of the respective housing cavity into a radially outer winding head cavity and a radially inner rotor cavity, in particular the radially inner rotor cavity forms the air flow cavity according to the application. In this case, in particular the radially inner rotor cavity of the electric machine is embedded in the air circuit. In this context, the air inlet opens into the rotor cavity on the inlet side, while the air outlet opens into the rotor cavity on the outlet side.

[0015] Alternatively and / or additionally, a rotor internal cooling can be provided, in which the rotor is part of a rotor hydraulic circuit. The rotor hydraulic circuit can likewise be largely separated from the air circuit and the stator hydraulic circuit.

[0016] The above-mentioned coolant separation between the winding head cavity and the radially inner rotor cavity forms a rotor cavity bottom. During operation of the electric machine, leakage coolant that has overflowed from the winding head cavity and / or leakage coolant that has overflowed from the rotor internal cooling or coolant that has overflowed from the bearing can collect on the rotor cavity bottom. It is preferred that the air outlet is arranged at the rotor cavity bottom of the rotor cavity on the outlet side. In this way, not only the air flow can be discharged through the air outlet, but additionally also the leakage coolant can be discharged from the rotor cavity on the outlet side. The mixture of air flow and leakage coolant can be introduced into the coolant reservoir by means of a return line.

[0017] In order to avoid the occurrence of coolant-containing air within the air gap, it is preferred that a separator is connected indirectly or directly before the air inlet in terms of process technology. By means of the separator coolant droplets can be removed from the air flow that flows into the electric machine housing through the air inlet.

[0018] In a first embodiment variant, the air outlet can be connected via a return line to the suction side of a return pump. The return pump serves as an air / coolant suction pump, in which a mixture of air flow and leaked coolant can be drawn off from the rotor chamber. In this way, a negative pressure is formed in the rotor chamber, whereby a pressure gradient is created between the transmission chamber and the rotor chamber which causes the air flow. Preferably, the return pump can be positioned within the coolant reservoir and have a riser line on its pressure side. The mixture of air flow and leaked coolant can flow through this riser line into the coolant reservoir. Furthermore, the air inlet can open into the air-filled upper interior space of the coolant reservoir without direct pump coupling.

[0019] Alternatively thereto, in a second embodiment variant, an air delivery pump serving as an air pressure pump can be arranged in the coolant reservoir. The air delivery pump can be flow-connected via its suction side to the air-filled upper interior space of the coolant reservoir. In this case, the air delivery pump can draw off air in the air-filled upper interior space of the coolant reservoir, which is delivered via an air delivery line to the air inlet and from there onwards to the electric machine. In this case, the air outlet can be connected via a return line to the coolant reservoir. Here, the return line can open into the coolant reservoir without direct pump coupling. Preferably, the return line within the coolant reservoir can transition into a riser line through which a mixture of air flow and leaked coolant flows into the coolant reservoir.

[0020] Preferably, a separator is connected before the air delivery pump on its suction side, by which coolant droplets are removed from the drawn-off air flow.

[0021] When the flow unit is configured as a dual pump, a design variant is obtained which is reduced in structural space and structurally simple, in which a delivery pump for stator cooling and / or for rotor internal cooling and a return pump or a delivery pump for air flow are combined into a dual pump. In this case, the individual pumps installed in the dual pump can be driven by a common drive shaft.

[0022] The coolant separation is configured as a closed-face type, that is to say without nozzles, and is in sealing contact with the end walls of the electric machine housing which lie opposite one another in the axial direction. The fluid-tight or flow-tight sealing of the winding head chamber from the rotor chamber does not necessarily have to be understood as a gas-tight, that is to say completely tight, sealing. Rather, it is possible for coolant to leak slightly through the sealing face of the coolant separation into the rotor chamber when the electric machine is in operation.

[0023] The rotor hydraulic circuit can be designed specifically for internal rotor cooling, in which the rotor shaft is constructed as a hollow shaft. The cavity of this hollow shaft can be at least partially traversed by coolant. After internal rotor cooling is complete, the coolant can be discharged into the rotor cavity, where it accumulates at the bottom of the rotor cavity. As already described, at least one rotor cavity outflow point can be constructed at the bottom of the rotor cavity through which the coolant can be returned to the coolant storage container. Attached Figure Description

[0024] Two embodiments of the present invention are described below with reference to the accompanying drawings.

[0025] The diagram shows:

[0026] Figure 1 and Figure 2 Schematic diagrams of the first and second embodiments of a coolant supply system are shown respectively;

[0027] Figure 3 shows a schematic diagram of a comparative example not included in this invention. Detailed Implementation

[0028] To better understand the invention, reference is first made to FIG3, in which a power unit for an axle of a two-wheeled vehicle is schematically shown. This power unit has an electric motor, which is exemplarily arranged laterally parallel to the axial direction of a flange shaft 3 that leads to the vehicle wheels. A stator 4 and a rotor 5 acting therein are arranged within the motor housing 2. The rotor shaft 6 is rotatably supported in bearing openings at the intermediate locations of axially opposed housing walls 8 and 9 of the motor housing 2, with rotating bearings 13 and 15 arranged in between.

[0029] The rotor shaft 6 of the motor is connected to the transmission input shaft 17 of the transmission device 19 in a non-rotatable manner, and its output is sent to two flange shafts 3. In Figure 3, the transmission device 19 consists of a transmission stage 18 and a shaft differential 20.

[0030] In Figure 3, stator 4 has multiple stator windings, among which... Figure 1 Only two stator windings 21 are shown. Each stator winding 21 has winding heads 23 and 25 on both sides along the axial direction, which extend into free end-side housing cavities 27. Each housing cavity 27 is embedded in a hydraulic circuit described later, by means of which oil can be loaded onto the corresponding winding head cavity 27 to cool the winding heads 23 and 25 of the stator 4. In each housing cavity 27, an oil / air mixture moves in the form of eddies around the high-speed rotating rotor shaft 5.

[0031] In the bearing assembly on the right side of Figure 3, the end of the rotor shaft 6 is rotatably supported in the hub section 31 by a rotating bearing 15.

[0032] The oil hydraulic circuit has an oil tank 35 which is connected to a delivery pump 37 by means of a suction line. From the delivery pump 37, a pressure line leads to oil supply lines 41, 43. By means of the supply line 41, oil is fed into a radially outer annular gap 45. From there, the oil is guided through radially outer stator channels 47 into a further annular gap 49 in the right-hand housing chamber 27. Both annular gaps 45, 49 are separated from the respective housing chamber 27 by oil jets 44. Each of the oil jets 44 has nozzles 46 distributed in the circumferential direction, through which nozzles oil can be sprayed into the respective housing chamber 27.

[0033] By means of the supply line 43, oil is guided through the rotor shaft 6 and, by means of a flow connection 51 in the radially inner rotor channels 53, into the right-hand housing chamber 27. In Figure 3, there is a tapping 54 at the housing bottom of the motor housing, by means of which tapping oil collected at the housing bottom is guided back into the oil tank 35 by means of a return pump 56.

[0034] Unlike in Figure 3, in Figure 1 or Figure 2 , according to the application, the stator 4 and its winding heads 23, 25 are no longer cooled by means of air / oil eddy currents. Rather, the housing chambers 27 of the motor housing 2 are divided by means of a coolant separation 57 into a radially outer annular winding head chamber 59 and a radially inner rotor chamber 61. The stator 4 with its stator winding 21 is positioned in the winding head chamber 59, while the rotor 5 is arranged in the radially inner rotor chamber 61 in a manner fluidically separated from the stator. Thus, according to the application, the stator 4 is no longer in contact with the eddy current cooling formed in the rotor chamber 61. Rather, in Figure 1 , the winding head chamber 59 is completely filled with coolant during operation of the motor, so that in particular the winding heads 23, 25 are completely encircled by the coolant, whereby an improved efficiency compared to the eddy current cooling can occur.

[0035] Firstly, the core of the application lies in the fact that the coolant is arranged in the device at the point where it is originally used, that is to say in the winding head chamber 59. Secondly, by means of the application, the coolant is kept as far away from the rotor chamber 61 as possible. That is to say, when using the oil jet cooling known from the prior art in Figure 3, the problem arises that, depending on the temperature of the coolant, different amounts of coolant adhere at the winding. In order to provide the pressure pump with a sufficient amount of coolant, therefore, relatively much coolant must be filled in.

[0036] As is known from Figure 1 , the motor is installed in the vehicle in a transverse arrangement, more precisely with the rotor shaft 6 running parallel to the vehicle transverse direction y, that is to say axially with respect to the axle. Furthermore, in Figure 1In the middle, the electric machine and the transmission 19 are arranged alongside one another in the vehicle transverse direction y. Furthermore, the transmission housing 63 of the transmission 19 is flange-mounted directly to the machine housing 2. In the transmission housing 63, the transmission 19 is positioned, according to Fig. 3, with a transmission stage 18 and with an axle differential 20.

[0037] A further core of the application consists in that the separate oil tank (reference 35 in Fig. 3) is dispensed with and, instead of this, the transmission housing 63 additionally also serves as oil tank or coolant reservoir with a double function, in which an oil column 65 is formed. Furthermore, the delivery pump 37 and the return pump 56 shown in Fig. 3 are combined into a common double pump 64. In the double pump 64, the delivery pump 37 and the return pump 56 are driven by the electric machine via a common (not shown) drive shaft.

[0038] Furthermore, as is known from Figure 1 In the transmission housing 63, a housing 67 which is open upwards is positioned as a hollow body on the bottom side, which separates an upwards open structure space 69 which is free of coolant from the oil column 65. The axle differential 20 partially projects into the structure space 69. In the normal case, jet lubrication takes place, in which oil is directed by means of the transmission supply line 42 in the direction of the axle differential 20. Coolant which drips from the axle differential 20 collects at the bottom of the housing 67 and is, if necessary, guided from there via a not shown outflow point into the return line 89, which is coupled to the suction side of the double pump 64. Instead of this, it is sufficient if the gears of the differential fling coolant out of the housing 67, if necessary. It is furthermore possible to configure small oil inflow openings in the housing 67 in order to still ensure emergency lubrication of the gears in the event of a pump failure.

[0039] During operation of the electric machine, oil is introduced into the winding head cavity 59 at a near-transmission inflow point 69 by means of the double pump 64 via the supply line 41. At an axially opposite, remote-from-transmission outflow point 71, oil is discharged from the winding head cavity 59. The winding head cavity outflow point 71 remote from the transmission can be embodied as a bulkhead, if possible, or as an overpressure valve. In order to also maintain oil in the winding head cavity 59 in the event of very high accelerations, in particular transverse accelerations, this bulkhead or overpressure valve is necessary. Furthermore, the winding head cavity outflow point 71 is in flow connection with the oil column 65 in the transmission housing 63 by means of a first return line 72, which opens into this oil column. Furthermore, an oil delivery line 80 branches off from the return line 72. By means of the oil delivery line 80, the bearings 15 in the hub section 31 are supplied with oil. Subsequently, the oil reaches the rotor cavity 61 via the bearings 15, from which it is drawn off via the return line 89.

[0040] In Figure 1In the rotor interior cooling by means of the coolant supply system, in which a temperature difference between the inner ring and the outer ring of the respective bearing 13, 15 is to be achieved, which is as small as possible. Figure 1 The oil guidance in the rotor shaft 6 is designed in such a way that not only the bearing 13 near the transmission but also the bearing 15 away from the transmission is cooled from the inside. The aim of this oil guidance is to achieve as small a temperature difference as possible between the inner ring and the outer ring of the respective bearing 13, 15.

[0041] According to this oil guidance, oil is fed by means of the supply line 43 into the hollow space of the rotor shaft 6 designed as a hollow shaft, that is to say up to the axial height of the rotary bearing 15 away from the transmission. From there, the oil is guided at the flow connection 76 away from the transmission into the rotor channel 53. In the rotor channel 53, the oil flows in the subsequent course in the opposite direction to the flow connection 77 near the transmission, at which the oil is again introduced back into the hollow space of the rotor shaft 6.

[0042] A further core of the application is that the coolant supply system has an additional closed air circuit. In this closed air circuit, the following components are fitted, namely the double pump 64, the air inlet 83, the rotor chamber 61 on the inlet side, the air gap 85 between the rotor 5 and the stator 4 and the air outlet 87 at the rotor chamber 61 on the outlet side. The air outlet 87 at the rotor chamber 61 on the outlet side is positioned on the bottom side of the coolant separation 57. During operation of the electric machine, the leakage coolant which escapes from the winding head chamber 59 and from the bearings 13 and 15 both of which are lubricated by oil collects on the bottom side of the coolant separation 57. In addition, leakage coolant which escapes from the rotor interior cooling also collects. By means of the air outlet 87, not only the leakage coolant but also, in addition, the air flow L which is described later and which circulates in the closed air circuit is discharged.

[0043] In Figure 1 the air outlet 87 is connected by means of the return line 89 to the suction side of a return pump integrated in the double pump 64. By means of the return pump integrated in the double pump 64, the mixture of air flow L and leakage coolant is drawn off from the rotor chamber 61 on the outlet side, in particular in the case of a negative pressure being formed in the rotor chamber 61 on the outlet side, as a result of which a pressure gradient which causes the air flow is produced between the transmission chamber 63 and the rotor chamber 61. The return pump integrated in the double pump 64 has a rising line 91 on its pressure side, through which the mixture of air flow L and leakage coolant flows into the transmission housing 63. This is achieved in the case of an overpressure being formed in the transmission housing 63.

[0044] Furthermore, as can be seen from Figure 1As is known from

[0045] In Figure 2 an alternative embodiment variant is shown in which an air delivery pump, not shown, is integrated in the double pump 64. The air delivery pump draws air from the air-filled upper interior space of the transmission housing 63, the air delivery pump being connected to the air inlet 83 by means of an air delivery line 93. Furthermore, in Figure 2 the air outlet 87 is connected to the transmission housing 63 by means of a return line 89. In Figure 2 the return line 89 opens into the transmission housing 63 without direct pump coupling. More precisely, the return line 89 ends in an ascending line 99 by means of which the mixture of air flow L and coolant is delivered into the transmission housing 63.

[0046] As is known from Figure 1 and Figure 2 an oil separator 97 is connected indirectly or directly before the air inlet 87. By means of the oil separator 97 coolant droplets are removed from the air flow L before the air flow L enters the inlet-side rotor chamber 61.

[0047] In Figure 1 and Figure 2 the motor is additionally integrated in the cooling water circuit K in which cooling water circulates around the outer circumference of the motor housing 2.

[0048] List of reference signs:

[0049] 2 motor housing

[0050] 3 flange shaft

[0051] 4 stator

[0052] 5 rotor

[0053] 6 rotor shaft

[0054] 8, 9 housing wall

[0055] 11 bearing opening

[0056] 13, 15 rotary bearing

[0057] 17 transmission input shaft

[0058] 18 transmission stage

[0059] 19. Transmission device

[0060] 20-shaft differential

[0061] 21 Stator windings

[0062] 23, 25 winding ends

[0063] 27 Motor cavity

[0064] 31. Wheel hub section

[0065] 33 Sealing elements

[0066] 35 Coolant Tank

[0067] 37 Transfer Pump

[0068] Supply pipelines 41, 42, and 43

[0069] 44 Oil injection ring

[0070] 45 Annular gap

[0071] 46 nozzles

[0072] 47. Radial outer stator channel

[0073] 49 Annular gap

[0074] 51 Flow connection part

[0075] 53. Radial internal stator channel

[0076] 54 Extraction Section

[0077] 56 Reflux Pump

[0078] 57 Coolant Separation Section

[0079] 59 Winding head cavity

[0080] 61 Rotor cavity

[0081] 63 Transmission device housing

[0082] 64 Dual Pumps

[0083] 65 Coolant column

[0084] 66 Ascending Pipeline

[0085] 67 Hollow body

[0086] 68. Hollow body outflow location

[0087] 69. Winding head cavity inflow point

[0088] 71. Outflow section of the winding head cavity

[0089] 72 another return conduit

[0090] 76 flow connection remote from the transmission

[0091] 77 flow connection proximate to the transmission

[0092] 80 coolant delivery conduit

[0093] 83 air inlet

[0094] 85 air gap

[0095] 87 air outlet

[0096] 89 return conduit

[0097] 91 riser conduit

[0098] 93 air delivery conduit

[0099] 97 oil separator

[0100] 99 riser conduit

[0101] L air flow

[0102] K cooling water circuit

Claims

1. A coolant supply system for an electrified axle power device having an electric machine, in the electric machine housing (2) of which a stator (4) cooperates with a rotor (5) which is spaced apart from the stator (4) by an air gap (85), wherein An electric machine interior space for rotor internal cooling and / or for stator cooling is loaded with coolant, wherein a coolant supply system has a flow unit (64) by means of which an air flow (L) can be generated, which flows through the air gap (85) in the axial direction, whereby the air gap (85) is kept free of coolant in order to reduce the rotor drag losses, characterized in that there are air flow chambers (61) on both sides of the rotor / stator arrangement in the axial direction, which are in flow connection with the air gap (85), which are divided into an inlet-side air flow chamber (61) and an outlet-side air flow chamber (61) with an air outlet (87), into which the air flow (L) flows through an air inlet (83), from which the air flow (L) flows.

2. The coolant supply system according to claim 1, characterized by The two air flow chambers (61), the air gap (85) and the flow unit (64) are embedded in an air circuit in which the air flow (L) generated by the flow unit (64) flows through the air inlet (83) into the inlet-side air flow chamber (61), can pass through the air gap (85) in the axial direction and can be fed back to the flow unit (64) from the outlet-side air flow chamber (61) through the air outlet (87).

3. The coolant supply system according to claim 1 or 2, characterized by The rotor / stator arrangement has housing chambers (27) on both sides in the axial direction, which are part of the end-side housing chambers (27), in which a coolant separation (57) is arranged in the electric machine housing (2), which divides each housing chamber (27) into a radially outer winding head chamber (59) and a radially inner rotor chamber (61), which is largely fluidically separated therefrom, into which the rotor is arranged and which forms the air flow chamber (61).

4. The coolant supply system according to claim 3, characterized by The air inlet (83) opens into the inlet-side rotor chamber (61), and the air outlet (87) opens into the outlet-side rotor chamber (61).

5. The coolant supply system according to claim 3, characterized by The winding head chamber (59) is part of a stator hydraulic circuit, which has an inflow point (69) at which coolant can be fed from a coolant storage container (63) into the winding head chamber (59), which has an outflow point (71) from which coolant can be fed from the winding head chamber (59) in the direction of the coolant storage container (63).

6. The coolant supply system according to claim 5, characterized by At the inflow point (69) coolant can be fed from the coolant storage container (63) into the winding head chamber (59) by means of a feed pump.

7. The coolant supply system according to claim 3, characterized by The coolant separation (57) forms the bottom of the rotor chamber (61), on which leakage coolant that has overflowed from the winding head chamber (59) and / or leakage coolant that has overflowed from the rotor internal cooling and / or coolant that has overflowed from the bearings (13, 15) collects, the air outlet (87) being arranged at the rotor chamber bottom of the outlet-side rotor chamber (61), through which not only leakage coolant but also the air flow (L) can be discharged.

8. The coolant supply system according to claim 1 or 2, characterized by A separator (97) is connected indirectly or directly before the air inlet (83), by means of which coolant droplets can be removed from the air stream (L).

9. The coolant supply system according to claim 7, characterized by The air outlet (87) is connected via a return line (89) to the suction side of a return pump, which withdraws the mixture of air stream (L) and leaked coolant from the rotor chamber (61) on the outlet side, and in the case of a negative pressure in the rotor chamber (61), which is thereby produced between the coolant reservoir (63) and the rotor chamber (61), a pressure gradient is produced which leads to the air flow, the return pump having a rising line (91) on its pressure side, through which the mixture of air stream (L) and leaked coolant flows into the coolant reservoir (63), and / or the air inlet (83) opens into the air-filled upper interior space of the coolant reservoir (63) without direct pump coupling, so that the air stream (L) through the air inlet (83) is produced on the basis of the pressure gradient between the coolant reservoir (63) and the rotor chamber (61).

10. The coolant supply system according to claim 7, characterized by An air delivery pump is arranged in the coolant reservoir (63), which withdraws air from the air-filled upper interior space of the coolant reservoir (63) and is connected via an air delivery line (93) to the air inlet (83), the air outlet (87) being connected to the coolant reservoir (63) via a return line (89), which opens into the coolant reservoir (63) without direct pump coupling.

11. The coolant supply system according to claim 6, characterized by The delivery pump for stator cooling and / or rotor internal cooling and the return pump or the delivery pump for the air stream (L) are combined into a double pump (64) forming a flow unit, in which the pumps can be driven by a common drive shaft, wherein the return pump serves to withdraw the mixture of air stream (L) and leaked coolant from the rotor chamber (61) on the outlet side, and the delivery pump for the air stream (L) withdraws air from the air-filled upper interior space of the coolant reservoir (63) and is connected via an air delivery line (93) to the air inlet (83).

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