DE102020120712A1 - Drive device for a motor vehicle - Google Patents

Abstract

The invention relates to a drive device (1) for a motor vehicle, having a coolant circuit (4), which is fluidically connected to an expansion tank (10), for cooling a device (2) to be cooled. It is provided that there is a further coolant circuit (5) for cooling a further device (3) to be cooled, which is fluidically connected to the coolant circuit (4) via a centrifugal separator (14).

Description

The invention relates to a drive device for a motor vehicle, having a coolant circuit, which is fluidically connected to an expansion tank, for cooling a device to be cooled.

From the prior art, for example, the publication EP 0 814 243 A1 known. This describes cooling for the cylinder of an internal combustion engine, in particular liquid cooling for the cylinder liner of a large diesel engine, in which the coolant is supplied to the cylinder liner at a temperature in a specified temperature range, with the coolant being preheated to the specified temperature range at least partially in the area of the cylinder .

Furthermore, the reference discloses DE 10 2006 039 681 A1 a reciprocating piston internal combustion engine of V-construction, with an inner V-area located between the cylinder banks above the crankcase and with a dry sump lubrication system, which has a dry sump reservoir. It is envisaged that the dry sump tank will be located in the inner V. Finally, the reference discloses US 10,202,889 B2 a centrifugal air separator.

It is the object of the invention to propose a drive device for a motor vehicle which has advantages over known drive devices, in particular enables particularly effective cooling of the drive device with at the same time low structural complexity.

According to the invention, this is achieved with a drive device for a motor vehicle having the features of claim 1 . In this case, a further coolant circuit is provided for cooling a further device to be cooled, which is fluidically connected to the coolant circuit via a centrifugal separator.

The drive device is used to drive the motor vehicle, ie to provide a drive torque aimed at driving the motor vehicle. The drive device has the device to be cooled. For example, during operation of the drive device or the device to be cooled, heat is generated which has to be dissipated by the device to be cooled. The device to be cooled is, for example, a drive assembly that is used to generate the drive torque. The drive unit is, for example, in the form of an internal combustion engine or an electric machine.

In order to cool the device to be cooled, the drive device has the coolant circuit. A coolant is circulated at least temporarily in the coolant circuit and is thereby supplied to the device to be cooled. In the device to be cooled, the coolant absorbs heat and dissipates it from the device to be cooled. The coolant circuit preferably has a heat exchanger or a cooler, via which the heat present in the coolant is dissipated from the coolant circuit, in particular in the direction of an external environment of the drive device. The heat exchanger or cooler is present, for example, in the form of a vehicle cooler, in particular in the form of a main cooler, of the motor vehicle. The radiator is designed in particular in such a way that ambient air flows against or flows through it while the motor vehicle is being driven.

The coolant circuit is fluidically connected to the expansion tank, in which coolant from the coolant circuit is temporarily stored. The expansion tank is used to compensate for different pressures in the coolant circuit, which occur, for example, at different temperatures. In addition, the expansion tank is used to supply additional coolant to the coolant circuit if there is not enough coolant in the coolant circuit. In order to be able to compensate for different pressures occurring in the coolant circuit, there is always a gas volume or air volume in the expansion tank.

During operation of the drive device and in particular of the coolant circuit, gas, in particular air, can separate from the coolant. The gas is then at least temporarily separate from the coolant in the coolant circuit and is circulated in it together with the coolant. However, this leads to a reduction in the efficiency of the coolant circuit, since, on the one hand, the gas has a lower heat capacity than the coolant and, on the other hand, it can cause the coolant circuit to become blocked in terms of flow technology. This is particularly the case if the gas enters a coolant pump of the coolant circuit together with the coolant. The gas causes a reduction in the capacity of the coolant pump, so that the coolant throughput through the coolant circuit, ie the volume flowing through the coolant circuit per unit of time or the mass flowing through the coolant circuit per unit of time, is reduced.

For this reason, the expansion tank is connected to the coolant circuit in such a way that that gas present in the coolant circuit is discharged into the expansion tank. For this purpose, the expansion tank is preferably located geodetically at a highest point of the coolant circuit in an intended installation position of the drive device. Due to its buoyancy compared to the coolant, the gas is pushed upwards and can thus enter the expansion tank, in which it is added to the gas volume. The coolant circuit is fluidically connected to the expansion tank in such a way that the gas remains in the expansion tank and does not escape from the expansion tank in the direction of the coolant circuit. This ensures efficient operation of the coolant circuit and a correspondingly high cooling capacity for the device to be cooled.

In addition to the coolant circuit, the drive device has the additional coolant circuit. The additional coolant circuit can preferably be operated independently of the coolant circuit. This means that the coolant circuit and the further coolant circuit each have a coolant pump, by means of which coolant can be circulated in them independently of the respective other coolant circuit or is circulated at least temporarily. The additional coolant circuit serves, for example, also to cool the device to be cooled or—additionally or alternatively—to cool a further device to be cooled.

If both the coolant circuit and the additional coolant circuit serve to cool the device to be cooled, the device to be cooled is supplied with both coolant from the coolant circuit and coolant from the additional coolant circuit for cooling. If the device is an internal combustion engine, then for example the coolant circuit is used to cool a cylinder crankcase and the other coolant circuit is used to cool a cylinder head.

However, it can also be provided that the drive device has the further device to be cooled in addition to the device to be cooled. The other device to be cooled is, for example, also a drive unit or at least has one. For example, the additional device to be cooled is in the form of an electrical machine or at least has one. In the latter case, the additional device to be cooled has, for example, an electrical component, in particular an inverter and/or an energy store, which is at least temporarily cooled using the additional coolant circuit.

The coolant circuit and the further coolant circuit are particularly preferably operated at different temperatures. Both the coolant circuit and the additional coolant circuit are set to a specific operating temperature. This means that they are operated in such a way that the coolant present in them at least temporarily corresponds to the respective operating temperature, for example directly downstream of the respective heat exchanger or cooler. The operating temperature of the coolant circuit is now higher than that of the other coolant circuit, for example by at least 20 K, at least 30 K, at least 40 K or at least 50 K. After the operating temperature has been reached, for example, the minimum temperature in the coolant circuit is higher than the maximum in the temperature of the coolant present in the further coolant circuit, in particular by one of the temperature differences mentioned.

It has already been explained that the two coolant circuits, ie the coolant circuit and the additional coolant circuit, can be operated independently of one another. To this end, they each have a coolant pump and a heat exchanger or cooler. In order to realize a space-saving configuration, however, the further coolant circuit is designed without an expansion tank, ie it does not have a separate expansion tank. However, since gas is also produced in the additional coolant circuit, which gas is separated from the coolant, for example, the additional coolant circuit also needs to be vented in order to achieve high efficiency.

For this reason, the further coolant circuit for venting is fluidically connected to the coolant circuit. However, an exchange of the coolant between the coolant circuit and another coolant circuit or vice versa is fundamentally undesirable, particularly if the two coolant circuits are operated at different temperatures, as explained above. In this case, the fluidic connection could lead to an equalization of the temperatures in the coolant circuits, so that the device to be cooled and/or the optional additional device to be cooled could not be adequately cooled. For this reason, it is now provided that the two cooling circuits are not directly connected to one another in terms of flow, but via the centrifugal separator.

The centrifugal separator is basically a mass force separator and can alternatively also be referred to as a cyclone separator. In the centrifugal separator it is flowed through Ends coolant imprinted a rotational movement, through which it comes particularly effectively to a separation of the gas. The centrifugal separator is particularly preferably configured as a tangential separator. In such a system, the coolant is introduced into the centrifugal separator in a tangential direction with respect to a longitudinal center axis of the centrifugal separator, so that the coolant is set in rotation. The coolant is forced downwards by gravity and thus returns to the further coolant circuit. The gas separated from the coolant in the centrifugal separator, on the other hand, can escape from the centrifugal separator in the direction of the coolant circuit.

The configuration of the drive device described achieves a particularly effective discharge of gas from the additional coolant circuit in the direction of the coolant circuit. The coolant circuit is fluidically connected to the expansion tank, so that gas discharged from the further coolant circuit into the coolant circuit is introduced into the expansion tank and retained in it. Correspondingly, both the coolant circuit and the further coolant circuit can be vented with the aid of the expansion tank and the centrifugal separator. Accordingly, a separate expansion tank for the additional coolant circuit can be dispensed with, resulting in a space-saving configuration.

A further development of the invention provides that the expansion tank is fluidically connected to the coolant circuit via an expansion tank supply line and an expansion tank return line and the centrifugal separator is connected to the further coolant circuit via a separator supply line and a separator return line. Both the coolant circuit and the further coolant circuit are each designed as closed circuits. The expansion tank and the centrifugal separator are now fluidically connected to these circuits. Coolant from the coolant circuit is supplied to the expansion tank via the expansion tank feed line and removed via the expansion tank return line in the direction of the coolant circuit.

Analogous to this, coolant is fed to the centrifugal separator from the further coolant circuit via the separator feed line and removed via the separator return line in the direction of the further coolant circuit. Preferably, the equalizing tank flow line has a smaller flow cross section than the equalizing tank return line and analogously the separator flow line has a smaller flow cross section than the separator return line. As a result, a higher flow rate is achieved in the respective flow line than in the associated return line. This achieves a particularly effective separation of the gas from the coolant.

A further development of the invention provides that the separator feed line opens into the centrifugal separator tangentially with respect to a longitudinal center axis of the centrifugal separator and the separator return line feeds into the centrifugal separator geodetically below the separator feed line in the axial direction when the drive device is installed in the correct position. The longitudinal central axis of the centrifugal separator runs, viewed geodetically, vertically or at least essentially vertically. The centrifugal separator is therefore aligned in such a way that, when the drive device is arranged as intended, it is perpendicular or at least approximately perpendicular to the ground on which the motor vehicle is located.

The centrifugal separator has a separator chamber which is round in cross-section with respect to the longitudinal central axis in order to impart the rotary motion to the coolant. For this purpose, the separator flow line opens tangentially into the centrifugal separator or the separator chamber. In the intended installation position, the separator flow line opens into the centrifugal separator or the separator chamber via the separator return line. Correspondingly, the coolant introduced through the separator feed line into the centrifugal separator flows due to the influence of gravity in the direction of the separator feed line and is forced into it.

The gas separated from the coolant in the centrifugal separator does not reach the separator return line due to its lower density compared to the coolant, but is discharged separately from the centrifugal separator in the direction of the coolant circuit. Such a configuration of the drive device enables a particularly effective separation of the gas from the coolant.

A further development of the invention provides that the centrifugal separator is designed in the shape of a funnel and has a flow cross section that decreases from the direction of the separator feed line and in the direction of the separator return line. The centrifugal separator or its separator chamber are in this respect at least partially conical or truncated. In any case, the flow cross section of the centrifugal separator is reduced in certain cases correct installation position of the drive device downwards, i.e. starting from the separator flow line in the direction of the separator return line.

It can also be provided that the separator feed line opens into a circular-cylindrical area of the centrifugal separator, which is followed by the funnel-shaped area of the centrifugal separator. The separator return line is connected to the funnel-shaped area and in this respect is fluidically connected to the circular-cylindrical area and finally to the separator flow line. This enables the gas to be cut off from the coolant in a particularly efficient manner.

A development of the invention provides that the centrifugal separator is fluidically connected via a ventilation line to the expansion tank or at a junction point to the expansion tank return line running from the expansion tank to the coolant circuit. The ventilation line opens into the centrifugal separator at a distance from the separator supply line and the separator return line. Particularly preferably, in the intended installation position of the drive device, it is connected to the centrifugal separator geodetically above or at least geodetically at the same level as the separator flow line. The ventilation line serves not only to ventilate the additional coolant circuit in the direction of the expansion tank, but also to fill the additional coolant circuit with coolant from the expansion tank. It can therefore also be referred to as a filling line or a filling and venting line.

For example, it opens centrally into the centrifugal separator with respect to the longitudinal center axis of the centrifugal separator, that is to say coaxially with the longitudinal center axis. It can be provided here that the ventilation line protrudes into the centrifugal separator, so that an outlet opening of the ventilation line is arranged in the centrifugal separator and is arranged, for example, geodetically below the separator flow line. Particularly preferably, however, the outlet opening is at least at the same level as the separator flow line or is even arranged above it, as seen in the vertical direction.

The ventilation line preferably rises steadily, starting from the centrifugal separator, in the direction of the expansion tank and/or the junction point. This means that a geodetic height of the ventilation line always remains at least the same or increases in the specified direction, but does not decrease. This serves to promote the gas in the direction of the expansion tank. If the ventilation line opens into the expansion tank return line at the junction point, it is preferably provided that the expansion tank return line also rises steadily starting from the junction point in the direction of the expansion tank. Such a design again serves to achieve a particularly effective separation of the gas from the coolant.

A development of the invention provides that the ventilation line opens into the centrifugal separator on a side facing away from the separator return line. For example, both the ventilation line and the separator return line open into the centrifugal separator centrally or coaxially with respect to the longitudinal center axis, namely on opposite sides. In this case, the separator return line preferably opens from below and the ventilation line from above, namely in each case when the drive device is arranged as intended. As a result, the gas can be discharged particularly effectively from the centrifugal separator in the direction of the coolant circuit, while the coolant from the centrifugal separator is fed back to the further coolant circuit.

A further development of the invention provides that the junction point is arranged geodetically above the centrifugal separator and below the expansion tank when the drive device is installed in the correct position. The confluence point at which the ventilation line is connected to the expansion tank return line should therefore be in the vertical direction between the centrifugal separator and the expansion tank. In any case, the ventilation line and the confluence point are arranged and designed such that the gas from the centrifugal separator is pushed towards the confluence point and via this into the expansion tank return line due to its lower density compared to the coolant.

The gas now present in the equalizing tank return line is then pushed further in the direction of the equalizing tank, again due to its lower density. Particularly preferably, the flow path between the centrifugal separator and the equalizing tank, consisting of the ventilation line, the junction point and the section of the equalizing tank return line between the junction point and the equalizing tank, runs continuously upwards. As a result, the gas is reliably discharged from the centrifugal separator in the direction of the expansion tank or into the expansion tank.

A development of the invention provides that the separator flow line branches off from the further coolant circuit geodetically above a junction point of the separator return line in the intended installation position of the drive device. The separator flow line branches off at a branch from the further coolant circuit, and the separator return line opens into it at the junction point. In order to ensure reliable venting of the further coolant circuit, the branch should be arranged above the junction point. The gas separated from the coolant is also forced upwards in the additional coolant circuit due to its lower density, so that it preferably collects comparatively far up in the additional coolant circuit, but at least above the junction point. Accordingly, it makes sense to realize the branch of the separator flow line at this point. It should be pointed out that the arrangement of the separator flow line above the junction point is advantageous, but not necessary for the proper functioning of the drive device.

A further development of the invention provides that the separator flow line branches off from the further coolant circuit at a geodetically highest point of the further coolant circuit when the drive device is installed in the correct position. In this regard, reference is made to the above statements. Branching off the separator flow line from the further coolant circuit at its geodetically highest point has the advantage that the gas that collects there can be discharged particularly effectively and directed in the direction of the centrifugal separator, via which it is ultimately fed to the coolant circuit and thus to the expansion tank. As already explained, such an embodiment makes it possible to dispense with a separate expansion tank for the further coolant circuit.

A development of the invention provides that the expansion tank is arranged geodetically above the coolant circuit and the additional coolant circuit when the drive device is installed in the correct installation position. This means that the expansion tank is not only arranged locally at the highest point in relation to the coolant circuit, but also in relation to the further coolant circuit. With such an arrangement, both coolant circuits can be reliably vented using the expansion tank. The arrangement of the expansion tank above the coolant circuits is advantageous, but not necessary for the proper functioning of the drive device.

• Figur eine äußerst schematische Darstellung einer Antriebseinrichtung mit einem Kühlmittelkreislauf und einem weiteren Kühlmittelkreislauf.

The invention is explained in more detail below with reference to the exemplary embodiments illustrated in the drawing, without the invention being restricted. It shows the only

• Figure shows an extremely schematic representation of a drive device with a coolant circuit and a further coolant circuit.

The figure shows a schematic representation of a drive device 1, which has a first device 2 to be cooled and a second device 3 to be cooled. To cool the first device 2 to be cooled, the drive device 1 has a coolant circuit 4 and to cool the second device 3 to be cooled, it has a further coolant circuit 5. In the coolant circuit 4, in addition to the first device 2 to be cooled, there is a cooler 6 and a coolant pump 7 before. Similarly, the coolant circuit 5 has a cooler 8 and a coolant pump 9 in addition to the second device 3 to be cooled.

Both the coolant circuit 4 and the coolant circuit 5 are each designed as closed circuits. They can also be operated independently of one another. This means that with the aid of the coolant pump 7 and 9 the coolant in the respective coolant circuit 4 or 5 can be circulated independently of the other coolant circuit 4 or 5 or is circulated at least temporarily.

To vent the coolant circuit 4, an expansion tank 10 is fluidically connected, namely via an expansion tank supply line 11 and via an expansion tank return line 12. In the exemplary embodiment shown here, the device 2 to be cooled is in the coolant circuit 4 downstream of the coolant pump 7 and the cooler 6 is downstream of the device to be cooled Device 2 arranged. In other words, the cooler 6 is fluidically connected to the coolant pump 7 via the device 2 to be cooled. On its side facing away from the device 2 to be cooled, the cooler 6 is fluidically connected again to the coolant pump 7, namely to a suction side of the coolant pump 7.

The expansion tank supply line 11 preferably branches off from the coolant circuit 4 downstream of the radiator 6, in particular closer to the radiator 6 than to the coolant pump 7. The expansion tank return line 12 opens out fluidically between the branch of the expansion tank supply line 11 from the coolant circuit 4 back into the latter. The expansion tank return line 12 is preferably connected to the coolant circuit 4 via a T-piece 13 .

In the further coolant circuit 5 the cooler 8 is connected to a pressure side of the coolant pump 9 . The second device 3 to be cooled is located downstream of the cooler 8 so that ultimately the second device 3 to be cooled is fluidically connected to the coolant pump 9 via the cooler 8 . On its side facing away from the cooler 8 , the second device 3 to be cooled is fluidically connected to a suction side of the coolant pump 9 .

To vent the coolant circuit 5 , it is fluidically connected to the coolant circuit 4 via a centrifugal separator 14 . The coolant circuit 4 is fluidically connected to the centrifugal separator 14 via a separator feed line 15 and a separator return line 16 . The centrifugal separator 14 is in turn connected to the additional coolant circuit 5 via a ventilation line 17 . For example, the ventilation line 17 opens into the expansion tank return line 12 via a T-piece 18 . However, it can also be connected to the expansion tank 10 itself.

In the intended installation position of the drive device 1 shown here, the separator feed line 15 opens geodetically above the separator return line 16 into the centrifugal separator 14 . Preferably, the ventilation line 17 in turn opens geodetically above the separator feed line 15 or at least at the same level in the centrifugal separator 14 . The ventilation line 17 and the expansion tank return line 12 rise steadily in the direction of the expansion tank 10 . This means that the height of the ventilation line 17 increases continuously, starting from the centrifugal separator 14 up to the T-piece. Likewise, the height of the expansion tank return line 12 increases steadily, at least starting from the T-piece 18 to the expansion tank 10, but preferably starting from the T-piece 13 to the expansion tank 10. As a result, the gas is effectively discharged into the expansion tank 10 .

The centrifugal separator 14 is funnel-shaped, so that it tapers on the side facing the separator return line 16, ie has a decreasing flow cross section. As a result, a particularly effective separation of a gas from the coolant in the further coolant circuit 5 is realized. For the sake of completeness, it should be pointed out that the separator return line 16 is connected to the further coolant circuit 5 via a T-piece 19, for example.

The configuration of the drive device 1 described enables the coolant circuit 5 to be bled without a separate expansion tank, but with the aid of the expansion tank 10, which is fluidically connected to the coolant circuit 4 and is only indirectly connected to the further coolant circuit 5 via the centrifugal separator 14. This enables a particularly compact configuration of the drive device 1 with a simultaneously high ventilation capacity.

Reference List

1

drive device

2

first device to be cooled

3

second device to be cooled

4

coolant circuit

5

coolant circuit

6

cooler

7

coolant pump

8th

cooler

9

coolant pump

10

surge tank

11

reservoir flow line

12

expansion tank return line

13

tee

14

centrifugal separator

15

separator flow line

16

separator return line

17

vent line

18

tee

19

tee

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• EP 0814243 A1 [0002]
• DE 102006039681 A1 [0003]
• US10202889B2 [0003]

Claims (10)

Drive device (1) for a motor vehicle, with a coolant circuit (4) connected in terms of flow to an expansion tank (10) for cooling a device (2) to be cooled, characterized by a further coolant circuit (5) for cooling a further device (3) to be cooled , which is fluidically connected via a centrifugal separator (14) to the coolant circuit (4). drive device claim 1 , characterized in that the equalizing tank (10) via an equalizing tank supply line (11) and an equalizing tank return line (12) to the coolant circuit (4) and the centrifugal separator (14) via a separator supply line (15) and a separator return line (16) to the further coolant circuit (5) is fluidically connected. Drive device according to one of the preceding claims, characterized in that the separator feed line (15) opens tangentially with respect to a longitudinal center axis of the centrifugal separator (14) into the centrifugal separator (14) and the separator return line (16) in the intended installation position of the drive device (1) geodetically below the separator feed line (15) opens into the centrifugal separator (14) in the axial direction. Drive device according to one of the preceding claims, characterized in that the centrifugal separator (14) is funnel-shaped and has a flow cross section decreasing from the direction of the separator flow line (15) and in the direction of the separator return line (16). Drive device according to one of the preceding claims, characterized in that the centrifugal separator (14) is connected via a ventilation line (17) to the expansion tank (10) or at a connection point to the expansion tank return line (12 ) is fluidically connected. Drive device according to one of the preceding claims, characterized in that the ventilation line (17) opens into the centrifugal separator (14) on a side remote from the separator return line (16). Drive device according to one of the preceding claims, characterized in that the junction point is arranged geodetically above the centrifugal separator (14) and below the expansion tank (10) when the drive device (1) is installed as intended. Drive device according to one of the preceding claims, characterized in that the separator flow line (15) in the intended installation position of the drive device (1) branches off geodetically above a junction point of the separator return line (16) into the further coolant circuit (5) from the further coolant circuit (5). Drive device according to one of the preceding claims, characterized in that the separator feed line (15) branches off from the further coolant circuit (5) at a geodetically highest point of the further coolant circuit (5) when the drive device (1) is installed in the correct position. Drive device according to one of the preceding claims, characterized in that the expansion tank (10) is arranged geodetically above the coolant circuit (4) and the further coolant circuit (5) when the drive device (1) is installed in the correct position.

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