Cooling circuit

Abstract

The invention relates to a cooling circuit (1) comprising an electric motor (6). A cooling fluid (F+L) consisting of liquid (F) and air (L) can flow through the electric motor (6) and cool it. In order to separate the liquid (F) and air (L) from the cooling fluid (F+L), the cooling circuit (1) has a separator (5).

Description

[0001] Cooling circuit

[0002] The invention relates to a cooling circuit with a cooling section through which cooling fluid flows and an electric motor cooled by cooling fluid according to the preamble of claim 1.

[0003] An electric motor is typically cooled in a cooling circuit using a coolant. The coolant flows through the motor, cooling individual motor components. Outside the motor, the coolant can then be cooled in a radiator and pumped back through the motor. The coolant can be, for example, an oil-air mixture. If the coolant is an oil-air mixture, it can also wet and cool hard-to-reach areas of the motor. However, pumping and cooling the coolant can be challenging. In particular, a foam can form in the oil-air mixture after it exits the motor, which is difficult to pump and cool.

[0004] EP 4 145 677 A1 discloses an electric motor which is cooled and circulated by an oil-air mixture.

[0005] The object of the invention is therefore to provide an improved or at least alternative embodiment for a cooling circuit of the generic type, in which the described disadvantages are overcome.

[0006] This problem is solved according to the invention by the subject matter of independent claim 1. Advantageous embodiments are the subject matter of the dependent claims. The present invention is based on the general idea of ​​separating the oil-air mixture exiting the engine into its components and thereby simplifying the pumping and cooling of oil in the cooling circuit.

[0007] The cooling circuit according to the invention comprises a cooling section through which a cooling fluid flows, with a starting point and an end point. The cooling circuit also includes an electric motor, the electric motor being arranged within the cooling section so that the cooling fluid flows through it. According to the invention, the cooling circuit comprises a first sub-circuit through which a liquid flows and a second sub-circuit through which air flows. The first sub-circuit and the second sub-circuit are fluidically merged at the starting point of the cooling section in such a way that the liquid and air are miscible to form the cooling fluid at the starting point of the cooling section. Furthermore, the first sub-circuit and the second sub-circuit are fluidly separated at the end point in such a way that the liquid and air can be separated from the cooling fluid at the end point of the cooling section.The cooling circuit also includes a separator, with the separator forming the endpoint of the cooling section.

[0008] In the cooling circuit according to the invention, the first sub-circuit is permeable to liquid and the second sub-circuit to air, thus separating the liquid and air in the two sub-circuits. This simplifies the pumping of the liquid separated from the air in the first sub-circuit. Furthermore, the cooling of the engine can be simplified and precisely controlled by regulating the flow rate of the liquid separated from the air. Since the heat in the cooling fluid is largely absorbed by the liquid, cooling the cooling fluid by cooling the liquid separated from the air can be sufficiently effective. This reduces the volume of the medium to be cooled and thereby improves the cooling of the medium itself – in this case, the liquid. Simultaneously, the engine can be cooled by the cooling fluid, which consists of the liquid and air.A liquid-air mixture can be cooled effectively. Specifically, the volume of the cooling fluid is greater than the volume of the pure liquid due to the addition of air, and therefore the velocity of the cooling fluid in the cooling section is higher than the potential velocity of the pure liquid. This also increases the heat transfer coefficient.

[0009] Mixing in air allows the coolant to be distributed more effectively within the engine, thus improving cooling. In particular, the coolant can then reach and cool areas of the engine that are difficult to access with the coolant alone.

[0010] The cooling fluid in question is a liquid-air mixture. The liquid can be oil, and consequently, the cooling fluid can be an oil-air mixture. It is understood that the liquid, once separated from the air, may still contain a certain residual amount of air. However, this residual air content is so small that it does not negatively affect the function of the pump designed to pump the pure liquid or the function of the cooler designed to cool the pure liquid. Experience has shown that this residual air content is less than 20% when using oil as the liquid.

[0011] In one possible embodiment, the motor can have a hollow shaft with an axis of rotation, a rotor non-rotatably connected to the hollow shaft, and a stator that accommodates the rotor and the hollow shaft. The hollow shaft can have an axially oriented interior, the rotor at least one radially outwardly oriented rotor channel, and the stator at least one axially oriented stator channel. The terms "axial" and "radial" refer to the axis of rotation of the motor's hollow shaft. The inner channel can be located in the hollow shaft, the rotor channel in or on the rotor, and the stator channel in or on the stator. The inner channel of the hollow shaft, the rotor channel of the rotor, and the stator channel of the stator can be fluidically connected and form a cooling path for the motor. The cooling section can then be formed, at least partially, by the motor's cooling path.In this cooling path, the motor can be cooled by the flow of cooling fluid. In particular, the stator can be cooled by the cooling fluid flowing in the stator channels.

[0012] It is conceivable that the starting point of the cooling path is located at the motor. This allows for a particularly compact design of the cooling circuit or cooling section. The starting point of the cooling path can also be located within the motor itself. For example, it is conceivable that the starting point of the cooling path is located in the inner channel of the hollow shaft. Here, the cooling fluid can be generated directly within the motor and circulated through it without pressure losses. The end point of the cooling path can also be located at the motor. Here, too, a particularly compact design of the cooling circuit or cooling section can be achieved. It is also conceivable that the second sub-circuit is formed and / or configured at least partially within the motor. This reduces the air's path from the end point to the starting point in the second sub-circuit.

[0013] The cooling circuit can include a first expansion tank, which can be arranged in the first sub-circuit so that the fluid flows through it. The cooling circuit can also include a return line, which can connect the first expansion tank to the second sub-circuit via an air-conducting line. The fluid, separated from the air, can be collected and temporarily stored in the first expansion tank. Furthermore, the fluid can be further separated from the air in the first expansion tank by gravity. The air separated from the fluid in the first expansion tank can then be returned to the second sub-circuit via the return line. Simultaneously, temperature-related volume changes of the fluid can also be compensated for via the return line.

[0014] The return line can, in particular, connect the first expansion tank to the second sub-circuit via an air-conducting line adjacent to the starting point. This allows the air from the first expansion tank to be routed to the cooling section via a short path. Alternatively, the return line can connect the first expansion tank to the second expansion tank via an air-conducting line.

[0015] As mentioned above, the cooling circuit can include a pump for circulating the liquid, and the pump can be positioned in the first sub-circuit so that the liquid flows through it. The cooling circuit can also include a cooler for cooling the liquid, and the cooler can be positioned in the first sub-circuit so that the liquid flows through it. Finally, the cooling circuit can include a filter for filtering the liquid, and the filter can be positioned in the first sub-circuit so that the liquid flows through it.

[0016] The second sub-circuit may have an externally open vent. Air can escape from the second sub-circuit through this vent, thereby compensating for temperature-related volume changes in the cooling circuit. A protective filter may be installed upstream of the vent to protect it from the ingress of dirt and water from the environment and to protect the environment from the ingress of the fluid.

[0017] The cooling circuit can include a second expansion tank, and this second expansion tank can be arranged in the second sub-circuit so that air can flow through it. The second expansion tank can be closed to the outside and have a variable volume. Temperature-related volume changes in the cooling circuit can be compensated for by changing the volume of the second expansion tank. In this case, the second sub-circuit can therefore be completely closed to the outside.

[0018] The motor can have an impeller, and the impeller can be fluidically connected upstream of the starting point in the second sub-circuit. The impeller can then convey air from the end point to the starting point in the second sub-circuit.

[0019] The separator can have an inlet for the cooling fluid, a first outlet for the fluid, and a second outlet for air. The separator can be fluidically connected to the cooling section via the inlet, to the first sub-circuit via the first outlet, and to the second sub-circuit via the second outlet. Within the separator, the fluid and air can be separated and fed separately to the respective sub-circuits. Advantageously, the first outlet can be located at the lowest point of the separator, allowing the fluid to flow to it under the influence of gravity. The second outlet can be advantageously located above the first outlet, preventing air from rising to it and liquid from reaching it.The separator can have an interior space and an impact wall that at least partially delimits the interior space from the outside, for the cooling fluid to impact. The impact wall can be fluidically located downstream of the inlet and fluidically located upstream of the first and second outlets. The inlet can be arranged in the interior space such that the cooling fluid can flow from the inlet onto the impact wall. At the impact wall, the fluid, due to its higher inertia, can separate from the air and, under the influence of gravity, settle downwards along the impact wall towards the first outlet. Air, on the other hand, can rise along the impact wall due to its lower inertia and be directed towards the second outlet. As described above, the first outlet can advantageously be located below the second outlet at the lowest point of the separator or its interior space.

[0020] The separator can have at least one upstream element arranged in the interior, with all upstream elements being fluidically connected upstream of the impact wall. At least one of the upstream elements can be designed with a nozzle plate to accelerate the cooling fluid towards the impact wall. The nozzle plate accelerates the cooling fluid, thereby improving the separation of the liquid from the air. At least one of the upstream elements can be designed with a liquid-repellent fleece. The fleece can, for example, be attached to a flowable carrier. The liquid can settle on the fleece, while air flows through it, allowing the liquid and air to be at least partially separated before reaching the impact wall. Overall, the separation elements ensure a clean separation of the liquid and air.If the separator has a nozzle plate and a fleece, the nozzle plate can be fluidically connected upstream of the fleece. Alternatively or additionally, the separator can have at least one downstream element arranged in the interior, with all downstream elements being fluidically connected upstream of the first outlet and / or fluidically downstream of the impact wall. At least one of the downstream elements can be designed as a perforated plate for defoaming the liquid. The perforated plate allows the liquid, already separated at the impact wall, to be freed of any remaining air or air bubbles. This further reduces the residual air content in the liquid. At least one of the downstream elements can be designed as a baffle plate. The baffle plate prevents sloshing noises generated by the liquid.

[0021] Alternatively or additionally, the separator can have a bypass path for the liquid already separated from air within the cooling fluid. This bypass path can fluidically connect the inlet to the first outlet around the impact wall. The bypass path allows the liquid, already separated from air, to flow directly to the first outlet without needing to be routed to the impact wall. This reduces the volume of cooling fluid flowing through the impact wall and / or upstream elements, allowing for more effective separation of this fluid into liquid and air.

[0022] The separator can, for example, be attached directly to the motor, so that a motor outlet for discharging the cooling fluid is directly connected to a separator inlet. In this context, "directly" means that no additional connecting lines are located between the motor outlet and the separator inlet. Specifically, the separator can be in contact with or flanged to the motor. This reduces the path of the cooling fluid from the motor to the separator and thus the pressure losses in the cooling fluid. Furthermore, the velocity component of the cooling fluid generated by the rotor's rotation can be used in the separator to separate the liquid and air.

[0023] Further important features and advantages of the invention will become apparent from the dependent claims, the drawings and the associated description of the figures based on the drawings.

[0024] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0025] Preferred embodiments of the invention are shown in the drawings and are explained in more detail in the following description, wherein identical reference numerals refer to identical or similar or functionally identical components.

[0026] They show, each schematically

[0027] Fig. 1 shows a view of a cooling circuit according to the invention in a first embodiment;

[0028] Fig. 2 shows a view of the cooling circuit according to the invention in a second embodiment;

[0029] Fig. 3 shows a view of the cooling circuit according to the invention in a third embodiment; Fig. 4 shows a sectional view of a separator in a first embodiment in the cooling circuit according to the invention;

[0030] Fig. 5 shows a side view of a motor with a separator in a second embodiment in the cooling circuit according to the invention;

[0031] Fig. 6 shows a sectional view of the separator in the second embodiment in the cooling circuit according to the invention;

[0032] Fig. 7 shows a sectional view of the motor with the separator in the second embodiment in the cooling circuit according to the invention;

[0033] Fig. 8 shows a sectional view of a starting point of a cooling section in the motor in the cooling circuit according to the invention;

[0034] Fig. 9 shows a view of the cooling circuit according to the invention in the third embodiment with the separator in the second embodiment;

[0035] Fig. 10 shows a partial exploded view of the cooling circuit according to the invention in the third embodiment with the separator in the second embodiment.

[0036] Fig. 1 shows a view of a cooling circuit 1 according to the invention in a first embodiment. The cooling circuit 1 comprises a first sub-circuit 2, a second sub-circuit 3, and a cooling section 4. The first sub-circuit is permeable to a liquid F – for example, oil – and the second sub-circuit 3 is permeable to air L. In the cooling section 4, a cooling fluid F+L flows, which consists of the liquid F and air L to form a liquid-air mixture. Here and subsequently, the flow of the liquid F is indicated by solid lines, the flow of air L by dotted lines, and the flow of the cooling fluid F+L or the liquid-air mixture by dashed lines.

[0037] The cooling section 4 has a starting point 4a where sub-circuits 2 and 3 merge, allowing the liquid F and air L to mix to form the cooling fluid F+L. Furthermore, the cooling section 4 has an ending point 4b where sub-circuits 2 and 3 diverge, allowing the liquid F and air L to be separated from the cooling fluid F+L. Advantageously, the starting point 4a is fluidically connected upstream of the ending point 4b. Additionally, the starting point 4a of the cooling section 4 is fluidically connected downstream of sub-circuits 2 and 3, and the ending point 4b of the cooling section 4 is fluidically connected upstream of sub-circuits 2 and 3. The ending point 4b of the cooling section 4 is formed by a separator 5, the design of which is explained in more detail below with reference to Figures 4 and 6.

[0038] In cooling section 4, a motor 6 is arranged so that cooling fluid F+L flows through it. The motor 6 includes an impeller 7, which is arranged in the second sub-circuit 3 and conveys air L in the second sub-circuit 3. The construction of the motor 6 is explained in more detail below with reference to Fig. 7. In the first sub-circuit 2, a filter 8 for filtering the liquid F, a cooler 9 for cooling the liquid F, and a pump 10 for pumping the liquid F are arranged. Furthermore, a first expansion tank 11 is arranged in the first sub-circuit 2, in which the liquid F can be temporarily collected. The first expansion tank 11 is connected to the second sub-circuit 3 via an air return line 12. In the second sub-circuit 3, an externally open vent 13 is arranged to compensate for volume changes in the cooling circuit 1. A protective filter 14 is located upstream of the vent 13 to protect the cooling circuit 1.The second sub-circuit 3 is to be protected from dirt and water from the environment, and the environment from liquid F. The return line 12 opens into the second sub-circuit 3 before the vent point 13.

[0039] In the cooling circuit 1 of the first embodiment, the liquid F in the first sub-circuit 2 and air L in the second sub-circuit 3 flow to the starting point 4a of the cooling section 4 and are mixed there to form the cooling fluid F+L. The starting point 4a is located inside the motor 6, as will be explained in more detail below with reference to Figures 7 and 8. In the cooling section 4, the cooling fluid F+L flows through the motor 6 and cools it. Since the volume of the liquid F is increased by the addition of air L, the flow velocity in the cooling section 4 is higher than it would be, for example, without the addition of air. This also results in a higher heat transfer coefficient and thus more effective cooling of the motor 6. At the end point 4b, the liquid F and air L are separated from each other by means of the separator 5 and fed back into the sub-circuits 2 and 3. In the first sub-circuit 2, the pure liquid F then flows.Liquid F separated from air, so that the cooler 9 and the pump 10 do not lose any power due to the air content.

[0040] Fig. 2 shows a view of the cooling circuit 1 according to the invention in a second embodiment. In the second embodiment, the cooling circuit 1 has a second expansion tank 15, which is fluidically connected downstream of the end point 4b in the second sub-circuit 3. Air L can be temporarily collected in the second expansion tank 15, thus compensating for volume changes in the cooling circuit 1. The second expansion tank 15 is closed to the outside and has a variable or pressure-dependent volume. The return line 12 opens into the second sub-circuit 3 upstream of the second expansion tank 15. A check valve 16 is also arranged in the return line 12, which prevents air L from flowing back into the first expansion tank 11.

[0041] Fig. 3 shows a view of the cooling circuit 1 according to the invention in a third embodiment. Here, the return line 12 from the first expansion tank 11 opens into the second sub-circuit 3 adjacent to the starting point 4a of the cooling section 3. This shortens the path from the first sub-circuit 3 to the cooling section 4. The return line 12 can be formed, at least partially, within the motor 6 or in a housing of the motor 6. The second sub-circuit 3 itself can also be formed, at least partially, within the motor 6 or in a housing of the motor 6.

[0042] Fig. 4 shows a sectional view of the separator 5 in a first embodiment within the cooling circuit 1 according to the invention. The separator 5 comprises an interior space 17 and an impact wall 18 that delimits the interior space 17 at least partially to the outside. The separator 5 also has an inlet 19, a first outlet 20, and a second outlet 21. The inlet 19 is fluidically connected to the cooling section 4, the first outlet 20 to the first sub-circuit 2, and the second outlet 21 to the second sub-circuit 3. The impact wall 18 is fluidically connected downstream of the inlet 19 and fluidically upstream of the outlets 20 and 21. Advantageously, the first outlet 20 is located at the lowest point of the interior space 17, so that the liquid F can settle towards the first outlet 20 under the influence of gravity.The second outlet 21, on the other hand, is located above the first outlet 20, allowing air L to rise and thus be separated from the liquid F. The separator 5 also includes a bypass path 22 that connects the inlet 19 with the first outlet 20 around the impact wall 18 or directly.

[0043] Two upstream elements 23 are arranged in the interior 17 of the separator 5 and are fluidically connected upstream of the impact wall 18. One upstream element 23 is a nozzle plate 24 for accelerating the cooling fluid F+L towards the impact wall 18, and the other upstream element 23 is a fleece 25a attached to a flowable carrier 25b. The fleece 25a is made of a material that repels the liquid F, so that the liquid F deposited on the fleece 25a can flow downwards to the first outlet 20. Furthermore, two downstream elements 26 are arranged in the interior 17 of the separator 5 and are fluidically connected downstream of the impact wall 18 and fluidically upstream of the first outlet 20. One downstream element 26 is a perforated plate 27 for defoaming the liquid F and the other downstream element 26 is a splash plate 37 for preventing sloshing noises.

[0044] The cooling fluid F+L, or the liquid-air mixture, flows into the separator 5 via the inlet 19. The liquid F, already separated from the air L in the cooling fluid F+L, is routed directly to the first outlet 20 via the bypass path 22. The remaining cooling fluid F+L is directed to the nozzle plate 24 and accelerated. The accelerated cooling fluid F+L flows over the fleece 25a, where the liquid F partially deposits, and then impacts the impact wall 18. The liquid F deposits on the impact wall 18 and is directed to the first outlet 20. At the first outlet 20, the liquid F is also defoamed by the perforated plate 27. Air, on the other hand, rises to the second outlet 21 and is directed to the second sub-circuit 3.

[0045] Fig. 5 shows a side view of the motor 6 with the separator 5 in a second embodiment of the cooling circuit 1 according to the invention. Here, the separator 5 is attached directly to the motor 6, with an outlet 28 of the motor 6 being fluidically connected directly to the inlet 19 of the separator 5 without any additional lines. The cooling fluid F+L flows from the motor 6 directly into the separator 5 via the outlet 28 of the motor 6 – see also Fig. 7 – and the inlet 19. In the second embodiment of the separator 5, the velocity component generated by the motor 6 in the cooling fluid F+L can also be used to separate the liquid F and air L.

[0046] Fig. 6 shows a sectional view of the separator 5 in the second embodiment of the cooling circuit 1 according to the invention. In the second embodiment, the interior 17 of the separator 5 is annular, with the inlet 19 and the second outlet 21 fluidically separated from each other by a web 29. The first outlet 20 is advantageously arranged at the lowest point of the interior 17. In the separator 5, as already indicated above, the velocity component generated by the motor 6 in the cooling fluid F+L is used to separate the liquid F and air L. Since a rotor of the motor 6 rotates in a rotational direction RR, the cooling fluid F+L is guided in the rotational direction RR, i.e., radially outwards, upon entering the interior 17. The impact wall 18 is then formed by a radially outer wall of the interior 17.

[0047] Fig. 7 shows a sectional view of the motor 6 with the separator 5 in the second embodiment of the cooling circuit 1 according to the invention. The motor 6 has a hollow shaft 30 with an axis of rotation RA, a rotor 31, and a stator 32. The hollow shaft 30 is rotationally connected to the rotor 31, and the stator 32 surrounds the hollow shaft 30 and the rotor 31 externally. The hollow shaft 30, the rotor 31, and the stator 32 are arranged in a housing 38. The cooling section 4 of the motor 6 allows the cooling fluid F+L or the liquid-air mixture to flow through it. For this purpose, a cooling path 33 is formed in the motor 6, which includes an axial inner channel 34 of the hollow shaft 30, several radially outwardly directed rotor channels 35 of the rotor 31 and several axially directed stator channels 36 of the stator 32, the cooling path 33 partially represents the cooling section 4.

[0048] The starting point 4a of the cooling section 4 is located in the motor 6. At starting point 4a, the liquid F from the first sub-circuit 2 and air L from the second sub-circuit 3 are combined and mixed to form the cooling fluid F+L. The cooling fluid F+L then flows through the cooling path 33 and cools the rotor 31 and, in particular, the stator 32 of the motor 6. The addition of air to the liquid F allows the cooling fluid F+L to better wet the rotor 31 and the stator 32, thus improving cooling. Furthermore, the cooling fluid F+L has a high velocity, which increases the heat transfer coefficient.

[0049] Fig. 8 shows a sectional view of the starting point 4a of the cooling section 4 in the motor 6 in the cooling circuit 1 according to the invention. Here it is particularly evident that air L and liquid F are supplied separately to the motor 6 and mixed within the motor 6 or in the inner channel 34 of the hollow shaft 30.

[0050] Fig. 9 shows a view and Fig. 10 shows a partial exploded view of the cooling circuit 1 according to the invention in the third embodiment with the separator 5 in the second embodiment. The fluidic connection of the separator 5 in the second embodiment with the motor 6 is particularly evident here.

Claims

Claims 1. Cooling circuit (1 ), - wherein the cooling circuit (1 ) has a cooling section (4) through which cooling fluid (F+L) flows, with a starting point (4a) and an end point (4b), - wherein the cooling circuit (1 ) has an electric motor (6) and the electric motor (6) is arranged in the cooling section (4) so ​​that cooling fluid (F+L) can flow through it, characterized in that - that the cooling circuit (1 ) has a first sub-circuit (2) through which a liquid (F) flows and a second sub-circuit (3) through which air (L) flows, - that the first sub-circuit (2) and the second sub-circuit (3) are fluidically merged at the starting point (4a) of the cooling section (4) in such a way that at the starting point (4a) of the cooling section (4) the liquid (F) and air (L) are miscible to form the cooling fluid (F+L), - that the first sub-circuit (2) and the second sub-circuit (3) are fluidically separated at the end point (4b) of the cooling section (4) in such a way that at the end point (4b) of the cooling section (4) the liquid (F) and air (L) can be separated from the cooling fluid (F+L), and - that the cooling circuit (1 ) has a separator (5) and the separator (5) forms the endpoint (4b) of the cooling section (4).

2. Cooling circuit (1) according to claim 1 , characterized in that, - that the motor (6) has a hollow shaft (30) with an axis of rotation (RA), a rotor (31) connected to the hollow shaft (30) and a stator (32) receiving the rotor (31) with the hollow shaft (30), - that the hollow shaft (30) has an axially oriented inner channel (34), and the rotor (31) has at least one radially outwardly oriented rotor channel (35) and the stator (32) at least one axially aligned stator channel (36) exhibits - that the motor (6) has a cooling path (33) and in the cooling path (33) the inner channel (34) of the hollow shaft (30) and the rotor channel (35) of the rotor (31) and the stator channel (36) of the stator (32) are fluidically connected to each other, and - that the cooling section (4) is formed at least partially by the cooling path (33) of the motor (6).

3. Cooling circuit (1) according to claim 1 or 2, characterized in that, - that the starting point (4a) is located on the motor (6), and / or - that the starting point (4a) is formed in the motor (6), and / or - that the starting point (4a) is located in the inner channel (34) of the hollow shaft (30), and / or - that the endpoint (4b) is located on the motor (6), and / or - that the second sub-circuit (3) is formed at least partially in the motor (6).

4. Cooling circuit (1) according to one of the preceding claims, characterized in that - that the cooling circuit (1 ) has a first expansion tank (11 ) and the first expansion tank (11 ) is arranged in the first sub-circuit (2) so that the liquid (F) can flow through it, and - that the cooling circuit (1 ) has a return line (12) and the return line (12) connects the first expansion tank (11 ) to the second sub-circuit (3) via an air-conducting connection.

5. Cooling circuit (1 ) according to claim 4, characterized in that the return line (12) connects the first expansion tank (11 ) with the second sub-circuit (3) immediately before the starting point (4a) of the cooling section (4) in an air-conducting manner.

6. Cooling circuit (1) according to one of the preceding claims, characterized in that, - that the cooling circuit (1 ) has a pump (10) for pumping the liquid (F) and the pump (10) is arranged in the first sub-circuit (2) so that the liquid (F) can flow through it, and / or - that the cooling circuit (1 ) has a cooler (9) for cooling the liquid (F) and the cooler (9) is arranged in the first sub-circuit (2) so that the liquid (F) can flow through it, and / or - that the cooling circuit (1 ) has a filter (8) for filtering the liquid (F) and the filter (8) is arranged in the first sub-circuit (2) so that the liquid (F) can flow through it.

7. Cooling circuit (1 ) according to one of the preceding claims, characterized in that the second sub-circuit (3) has an externally open venting point (13) for compensating volume changes in the cooling circuit (1 ), preferably with an upstream protective filter (14).

8. Cooling circuit (1) according to one of the preceding claims, characterized by - that the cooling circuit (1 ) has a second expansion tank (15) and the second expansion tank (15) is located in the second sub-circuit (3) is arranged to allow air (L) to flow through it, and - that the second expansion tank (15) is closed to the outside and has a variable volume to compensate for volume changes in the cooling circuit (1 ).

9. Cooling circuit (1 ) according to one of the preceding claims, characterized in that the motor (6) has an impeller (7) and the impeller (7) is fluidically connected upstream in the second sub-circuit (3) of the starting point (4a) of the cooling section (4).

10. Cooling circuit (1) according to one of the preceding claims, characterized in that, - that the separator (5) has an inlet (19) for the cooling fluid (F+L), a first outlet (20) for the liquid (F) and a second outlet (21) for air (L), and - that the separator (5) connects to the cooling section via the inlet (19). (4) is fluidically connected via the first outlet (20) to the first subcircuit (2) and via the second outlet (21) to the second subcircuit (3).

11. Cooling circuit (1) according to claim 10, characterized in that, - that the separator (5) has an interior (17) and an interior (17) impact wall that delimits at least some areas to the outside (18) to impact the cooling fluid (F+L), and - that the impact wall (18) is fluidically downstream of the inlet (19) and fluidically upstream of the first outlet (20) and the second outlet (21).

12. Cooling circuit (1) according to claim 11, characterized in that the separator (5) has at least one upstream element (23) arranged in the interior (17) and all upstream elements (23) are fluidically connected upstream of the impact wall (18), - wherein at least one of the upstream elements (23) is formed by a nozzle plate (24) for accelerating the cooling fluid (F+L) towards the impact wall (18), and / or - wherein at least one of the upstream elements (23) is formed by a fleece (25a) which is preferably attached to a flowable carrier (25b) and repels the liquid (F).

13. Cooling circuit (1) according to claim 11 or 12, characterized in that the separator (5) has at least one downstream element (26) arranged in the interior (17) and all downstream elements (26) are fluidically connected upstream of the first outlet (20) and / or fluidically connected downstream of the impact wall (18), - wherein at least one of the downstream elements (26) is formed by a perforated sheet (27) for defoaming the liquid (F), and / or - wherein at least one of the downstream elements (26) is formed by a baffle plate (37) to prevent sloshing noises caused by the liquid (F).

14. Cooling circuit (1) according to one of claims 10 to 13, characterized in that the separator (5) has a bypass path (22) for the liquid (F) present in the cooling fluid (F+L) and already separated from air (L), and the bypass path (22) fluidically connects the inlet (19) with the first outlet (20) around the impact wall (18).

15. Cooling circuit (1 ) according to one of the preceding claims, characterized in that the separator (5) is attached directly to the motor (6), such that an outlet (28) of the motor (6) for discharge of the cooling fluid (F+L) is fluidically connected directly to an inlet (19) of the separator (5) for supplying the cooling fluid (F+L). *****

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