EP3320197A1

EP3320197A1 - Coolant circuit for a liquid-cooled transmission

Info

Publication number: EP3320197A1
Application number: EP16728292.0A
Authority: EP
Inventors: Norbert Amann
Original assignee: Bayerische Motoren Werke AG
Current assignee: Bayerische Motoren Werke AG
Priority date: 2015-07-08
Filing date: 2016-06-08
Publication date: 2018-05-16
Anticipated expiration: 2036-06-08
Also published as: US10480389B2; EP3320197B1; DE102015212733A1; CN107532500A; CN107532500B; US20180066566A1; WO2017005438A1

Abstract

The invention relates to a coolant circuit (1) with an engine cooling circuit (10, 11) in which coolant can be circulated in order to cool an internal combustion engine (6, 8) that has a cylinder head cooling circuit (10) and a crankcase cooling circuit (11) separated from the cylinder head cooling circuit; a transmission cooling circuit (19) for cooling a transmission (20), said transmission cooling circuit branching off from the motor cooling circuit (10, 11); a valve (14) which is arranged in the transmission cooling circuit (19); and a controller (26) which is designed to open and close the valve (14) depending on an operating state of the internal combustion engine and/or the transmission. In particular, the transmission cooling circuit (19) branches off from the crankcase cooling circuit (11) to a section along which the crankcase cooling circuit (19) is separated from the cylinder head cooling circuit (10).

Description

Coolant circuit for liquid-cooled gearboxes

The invention relates to a coolant circuit with an engine cooling circuit and a branched from the engine cooling circuit transmission cooling circuit.

Modern high-performance transmissions, in particular dual-clutch transmissions, are also cooled with water in addition to oil cooling. In this case, coolant is diverted from the engine cooling circuit and for cooling the

Gear used. However, with this type of cooling has been shown that over long operating ranges, the relative warm coolant in the

Coolant circuit causes that in these operating areas, the transmission is heated rather than cooled. Only in high power ranges, this effect is reversed, so that the transmission is cooled.

There is therefore a need for improved cooling of

liquid cooled gearboxes.

It is an object of the present invention to provide a coolant circuit for cooling a transmission having improved cooling characteristics. This object is achieved with a coolant circuit according to claim 1, a motor vehicle according to claim 9 and a control method according to claim 12. Advantageous developments of the invention are the subject of the dependent claims. According to one embodiment of the invention, a coolant circuit is provided, with an engine cooling circuit in the coolant for cooling an internal combustion engine is circulated; a transmission cooling circuit for cooling a transmission, which branches off from the engine cooling circuit; a valve which is arranged at least in the transmission cooling circuit, and a controller adapted to the valve depending on a

Operating state of the internal combustion engine and / or the transmission to open and close. The operating state of the internal combustion engine may be determined, for example, by a throttle position, an engine speed and / or an engine torque. Further, the controller may be adapted to control (open and close) the valve depending on at least one of the following parameters: a

Coolant temperature, a crankcase temperature. As described above, it has been found that conventional

Low-horsepower coolant circuits heat the transmission sooner than cool it. Furthermore, this also adversely affects the heating speed of the internal combustion engine in the warm-up phase, which can have an influence on emissions and consumption. This is done by providing a switch-off option in the transmission cooling circuit, depending on the

Engine power, prevented. Since the engine can be cooled very effectively by the coolant at a high engine output, a flow of coolant through the transmission cooling circuit is permitted at a certain engine output as of which the cooling effect occurs.

According to a further embodiment of the invention, the engine cooling circuit comprises a cylinder head cooling circuit and, separately therefrom, a crankcase cooling circuit, the transmission cooling circuit branching from the crankcase cooling circuit, i. branches off on a portion along which the crankcase cooling circuit of the

Cylinder head cooling circuit is disconnected. The advantage that results from this coolant circuit is that in so-called. Split cooling engines, in which a separate crankcase and cylinder head cooling circuit is provided, the cylinder head cooling circuit is permeated permament and it is sufficient if the crankcase cooling circuit is only flowed through at a certain engine power. The inventor of this invention found that by coupling the transmission cooling circuit to the

Crankcase cooling circuit an additional, separate valve for the

Transmission cooling circuit can be saved because the crankcase and the transmission show similar cooling conditions and thus a

common valve for the transmission cooling circuit and the

Crankcase cooling circuit can be used. In this

Embodiment is the valve (the same valve) thus in

Transmission cooling circuit and arranged in the crankcase cooling circuit, i. the transmission cooling circuit and the crankcase cooling circuit are

identical at least at the entrance or at the outlet of the valve.

According to a further embodiment of the invention is a

Coolant circuit provided, wherein the crankcase cooling circuit comprises a crankcase water jacket, which around cylinder bores

is guided around, and the transmission cooling circuit downstream of a

Device for absorbing heat from the transmission, in particular a water jacket in the transmission housing or a heat exchanger for

Heat transfer with the transmission oil, opens into the crankcase water jacket. In particular, the valve is located downstream of the

Crankcase water jacket.

According to another embodiment of the invention

downstream of the valve, the cylinder head cooling circuit and the

Crankcase cooling circuit merged again.

According to a further embodiment of the invention, the engine cooling circuit branches at a branch into the cylinder head cooling circuit and the crankcase cooling circuit, wherein the transmission cooling circuit branches off from the crankcase cooling circuit downstream of the branch. According to another embodiment of the invention, the transmission cooling circuit branches off the crankcase cooling circuit downstream of the branch and upstream of a crankcase water jacket of the crankcase cooling circuit.

According to a further embodiment of the invention is a

Coolant circuit provided, wherein the crankcase cooling circuit downstream of the junction in a crankcase water jacket and a motor oil cooling circuit, which is adapted via a

Heat exchanger to cool an engine oil, branches, and wherein the

Transmission cooling circuit branches off from the engine oil cooling circuit.

According to a further embodiment of the invention is in the

Transmission cooling circuit provided a check valve. This

Check valve to prevent, especially in split-cooling system, with closed transmission cooling circuit valve of the

Crankcase water jacket and in the reverse direction of the

Transmission cooling circuit is flowed through.

According to a further embodiment of the invention, the

Branching formed by a coolant pump.

According to a further embodiment, the control is adapted, the valve depending on an engine speed and / or a

To open and close engine torque. Further, the controller may be adapted to control (open and close) the valve depending on at least one of the following parameters: a coolant temperature, a crankcase temperature.

According to another embodiment, the controller is adapted to open the valve only above a certain threshold of engine speed and / or engine torque. That is, the controller is adjusted to open the valve above the threshold and close below the threshold (including the threshold itself). In particular, the control is adjusted, the valve above the

Fully open and fully close below the threshold (including the threshold itself). Engine speed and engine torque determine engine performance. In this case, the controller may be adapted to open the valve only above a threshold value of the engine power of 70% of the maximum engine power, the so-called nominal engine power. In particular, the threshold is 80%.

In addition, the invention relates to a vehicle with a

Coolant circuit according to one of the preceding claims.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. These drawings show:

Figure 1 shows schematically a first embodiment of the

Coolant circuit according to the present invention;

FIG. 2 schematically shows a second embodiment of the invention

Coolant circuit according to the present invention, and

FIG. 3 schematically shows a third exemplary embodiment of the invention

Coolant circuit according to the present invention.

Figure 1 shows schematically a first embodiment of the

Coolant circuit according to the present invention. In particular, this coolant circuit in motor vehicles by coolant (for example, a mixture of glycol and water) flows through to a

Internal combustion engine and a liquid-cooled transmission, in particular a dual-clutch transmission to cool. Flow directions are in all Figures indicated by corresponding arrows in the respective flow paths.

The coolant circuit 1 comprises an engine cooling circuit and a transmission cooling circuit which extend together through a radiator 2, which is known to be cooled by a fan 3 in addition to the airstream, and cools a guided in the coolant circuit coolant in a known manner. From a radiator outlet 4, the coolant circuit continues to extend to a coolant pump 5, which may be a mechanical, an internal combustion engine, or electrically driven coolant pump. The internal combustion engine comprises a crankcase 6 with a plurality of cylinder bores 7 and a cylinder head housing 8 with the cylinder heads 9 belonging to the cylinder bores 7. The coolant circuit 1 is introduced into a cylinder head cooling circuit 10 and a crankcase cooling circuit at a branch formed by the coolant pump 5 in this embodiment Divided 1 1. However, the branch can also continue downstream of the coolant pump 5 by a

Coolant line junction are formed.

Within the crankcase 6 and the cylinder head housing 8 each cooling channels are formed in the housing material, which are guided around each cylinder bore 7 and each cylinder head 9 in the form of a water jacket. This crankcase water jacket 13 or

Cylinder head water jacket 12 is formed by cavities which extend over a certain height of the cylinder bores 7 and cylinder heads 9 and surround the cylinder bores or cylinder heads in an annular manner. These annular cavities are connected in series. In addition, these interconnected cavities are connected to an inlet and a drain, for example, are connected by the two outer cavities, one with an inlet and the other with a drain. After dividing into cylinder head cooling circuit 10 and crankcase cooling circuit 1 1, the cylinder head cooling circuit 10 performs the cylinder head water jacket 12 and the crankcase circuit 1 1 through the crankcase water jacket 13th

At the output of the crankcase water jacket 13 performs the

Kurbelgehäusekühlkreislauf 1 1 to a valve 14, which in

closed state the flow of coolant in the

Crankcase water jacket 13 stops and in the open state, the flow of coolant through the crankcase water jacket 13 permits. With regard to the coolant, the valve 14 preferably has a single input and a maximum of two outputs. The valve 14 may, for example

electromagnetically, for example with an electromotive

Worm drive, be operable. The output of the valve 14 leads into a thermal management module 15, which is responsible for the control of the cooling circuit 1, and from there back into the radiator second

Between the coolant pump 5 (or the branch) and the input to the crankcase water jacket 13 branches off an engine oil cooling circuit 1 6, which is a separate channel to the crankcase water jacket 13 in

Crankcase 6 is formed. The engine oil cooling circuit 16 passes through an engine oil water heat exchanger 17 in which the coolant cools an engine oil which lubricates and cools moving parts of the engine. For this purpose, on the one hand flows through the engine oil cooling circuit 1 6 the

Engine oil water heat exchanger 17 and separate thereof an unillustrated engine oil circuit. Downstream of the engine oil heat exchanger 17, the engine oil cooling circuit 16 is combined at a location 18 with the cylinder head cooling circuit 10 coming from the outlet of the cylinder head cooling circuit 12 and forwarded to the thermal management module 15, after which it is led back to the cooler 2.

From the engine oil cooling circuit 1 6 branches a transmission cooling circuit 19 for cooling a transmission 20 from, this is for example a

Double clutch. FIG. 1 shows that the Transmission cooling circuit 19 branches off in the region of the engine oil heat exchanger 17. However, the transmission cooling circuit 19 may branch off somewhere between the coolant pump 5 (or the branch) and the point 18 of the engine oil cooling circuit 1 6. The transmission cooling circuit 19 may also branch off from the crankcase water jacket 13. Likewise, the transmission cooling circuit 19 directly (indirectly shown in Fig. 1) of the crankcase cooling circuit 1 1 between the coolant pump 5 (or the branch) and the input to the crankcase water jacket 13 branch off. Preferably, the transmission cooling circuit 19 branches from

Crankcase cooling circuit 1 1 from, in particular at a location that is suitable in practice for such a connection. The transmission cooling circuit 19 leads to a device 21 for absorbing heat from the transmission 20, in particular a dual-clutch transmission. This device 21 is formed in this embodiment, a trained in the transmission housing

Water jacket, which is guided around hot components of the transmission 20 similar to the water jackets described above. Depending on the type of transmission, the device 21 could also be a heat exchanger that cools a transmission oil. Downstream of the device 21, the transmission cooling circuit 19 opens into the crankcase water jacket 13, preferably in the region of the outlet and preferably on the hotter side of the water jacket.

The valve 14, which is arranged at the outlet of the crankcase water jacket 13, is thus arranged in the transmission cooling circuit 19 by the introduction of the transmission cooling circuit 19 into the crankcase water jacket 13. If the valve 14 is closed, then a

Coolant flow in the transmission cooling circuit 19 prevented and the valve 14 is opened, this also allows a coolant flow in the transmission cooling circuit 19. To avoid a flow in the

Crankcase water jacket 13 and a backflow in the

Transmission cooling circuit 19, with the valve 14 closed, is in

Transmission cooling circuit 19, a check valve 22 is provided, which only a flow from the engine oil cooling circuit 1 to 6 Crankcase water jacket 13 allows. This valve 14 is in this embodiment depending on an operating condition of

Internal combustion engine and / or the transmission open and closed. The control of the valve 14 is carried out by a controller 26 in the form of an electrical circuit or by a computing unit (e.g.

programmable or preprogrammed) can be implemented. In Figure 1, the controller 26 is associated with the thermal management module 15, however, the controller 26 may also be a stand-alone controller, part of a motor controller, the motor controller itself, or any other suitable controller. The controller 26 may control the valve 14 to open or close, thereby controlling a flow rate through the valve 14. In addition or alternatively, the controller 26 may also control the valve 14 clocked, so that this opens and closes with a certain tact, thus a desired

To achieve flow rate. In addition, the controller 26 may also control the valve 14 to narrow or expand a flow area such that a certain flow rate of refrigerant is achieved.

The basis for the control of the valve 14 by the controller 26 is the operating state of the internal combustion engine and / or the transmission.

This includes at least one of the following parameters:

- Engine speed of the internal combustion engine

- Torque of the internal combustion engine

- engine power (determined by engine power and engine torque)

- Throttle position

- Transmission input speed

- Transmission output speed

- Transmission input torque

- Transmission output torque

- coolant temperature (measured via a temperature sensor) - Crankcase temperature (measured via a temperature sensor)

- Transmission case temperature (via a temperature sensor

measured)

Preferably, the controller 26 is adapted to open and close the valve 14 depending on engine speed and / or engine torque, wherein one or more of the above-mentioned parameters may be additionally included in the controller. For example, the valve 14 could be controlled depending on engine speed, engine torque, coolant temperature, and crankcase temperature. By a certain engine speed and a certain engine torque results in an engine power. For example, the valve 14 is opened above a certain engine power and closed below this engine power. More preferably, the valve 14 opens from an engine output of 60%, more preferably opens the valve 14 from an engine power of 70%, even more preferably opens the valve 14 from an engine power of 80%. The control of the valve 14 can also be realized so that in the control 26 control characteristics or

Control table assignments certain values of the above parameters are associated with certain switching states of the valve 14.

It should also be mentioned that in the closed state of the valve 14, coolant can continue to flow through the engine oil cooling circuit 16. The valve 14 therefore does not switch the engine oil cooling circuit 16.

FIG. 2 schematically shows a second embodiment of the invention

Coolant circuit according to the present invention. In Figure 2

For example, like reference numerals indicate the same or similar components, and reference is made to the description of the first embodiment to avoid repetition. Only differences to the first embodiment will be described here. For example, an outlet of the crankcase water jacket 13 and the cylinder head water jacket 12 is not disposed at the outer end of the respective water jacket, but in the area of the penultimate

Cylinder bore or cylinder head, causing the

Change flow conditions in the respective water jacket something, as represented by corresponding flow arrows.

The preferred embodiment of the device 21 is a transmission oil heat exchanger, but may also be the water jacket already described in the first embodiment.

In the second embodiment, a bypass line 29 is additionally provided, via which the thermal management module 15 can bypass the radiator 2 if necessary. For example, to achieve a faster heating of the coolant.

A heating heat exchanger 23 is connected to the heat management module 15 and is supplied from the heat management module 15 with coolant, if necessary, which is guided back into the heat management module 15 downstream of the heating heat exchanger 23.

Parallel to the cylinder head water jacket 12, a cooling circuit for cooling a cylinder head integrated manifold 24 is connected. Between an outer end of the cylinder head water jacket 12 and an outlet of the heating heat exchanger 23, a cooling circuit for an exhaust gas turbocharger 25 is connected.

The engine oil cooling circuit 16 corresponds to the transmission cooling circuit 19, because as shown in FIG. 2, the engine oil heat exchanger 17 is arranged upstream and in series with the device 21. This

Engine oil cooling circuit 1 6 or transmission cooling circuit 19 branches downstream the coolant pump 5 (or the branch) and upstream of the input of the crankcase water jacket 13 from. However, the invention is not limited thereto, so that the engine oil cooling circuit 1 6 and the

Transmission cooling circuit 19 may both be parallel to each other, both downstream of the coolant pump 5 (or the branch) and upstream of the input of the crankcase water jacket 13th

branch off and open both again in the crankcase water jacket 13.

For completeness, it should be mentioned that in Figure 2 the

Connections between the motor oil heat exchanger 17 and the point 18 and between the point 18 and the thermal management module 15, no points of contact with the engine oil cooling circuit 16 or the

Cylinder housing water jacket 13 have.

FIG. 3 schematically shows a third exemplary embodiment of the invention

Coolant circuit 1 according to the present invention. In Fig. 3, like reference characters represent the same or similar components, and reference is made to the description of the foregoing embodiments unless otherwise described below.

The cooling circuit 1 comprises, as in the preceding

Embodiments, an engine cooling circuit, which a

Cylinder head cooling circuit 10 and a crankcase cooling circuit 1 1 has. The cylinder head cooling circuit 10 and the

Crankcase cooling circuit 1 1 preferably extend together as engine cooling circuit through the radiator 2. Downstream of the radiator 2, the engine cooling circuit divides on the coolant pump 5 and the branch in the separated sections of the

Cylinder head cooling circuit 10 and the crankcase cooling circuit 1 1 on. After flowing through the respective water jackets 12 and 13 of the cylinder head cooling circuit 10 and the crankcase cooling circuit 1 1 again brought together, for example in the thermal management module 15, and lead back to the radiator. 2

In the embodiment of FIG. 3, the branch is in the

Cylinder head cooling circuit 10 and the crankcase cooling circuit 1 1 provided on the coolant pump 5 or downstream thereof. Of the

Branching leads the cylinder head cooling circuit 10 through the

Cylinder head water jacket 12 and from there via an output line 27 in the thermal management module 15. The engine oil cooling circuit 1 6 is coupled in this embodiment, the cylinder head cooling circuit 10. More specifically, the engine oil cooling circuit 1 6 branches off from the cylinder head water jacket 12 and is located at a downstream location of the cylinder head water jacket 1 6

Cylinder head water jacket 12 again returned to the cylinder head water jacket 12. After the branching from the cylinder head water jacket 12, the engine oil cooling circuit 1 6 thus flows through the

Engine oil water heat exchanger 17 and flows back into the

Cylinder head water jacket 12. Reference is made to the description of the preceding exemplary embodiments for engine oil heat exchanger 17.

Between the branching in cylinder head cooling circuit 10 and

Crankcase cooling circuit 1 1 on the one hand and the input of

Crankcase water jacket 13 on the other hand, or in other words downstream of the branch and upstream of the

Crankcase water jacket 13 branches off the transmission cooling circuit 19. The inlet of the crankcase water jacket 13 is defined as the point where the crankcase circuit 13 opens into a cavity surrounding a cylinder for the first time after entering the crankcase. At the point at which the transmission cooling circuit 19 branches off from the crankcase cooling circuit 1 1, the valve 14 is provided. The valve 14 is preferably an electric valve, but may also correspond to one of the aforementioned embodiments. In particular, the valve 14 forms the

Branch of the transmission cooling circuit 19 from the crankcase cooling circuit 1 1. The valve 14 may, depending on a current flow, a flow of coolant in both the crankcase cooling circuit 1 1 and in the

Allow transmission cooling circuit 19 or prevent. Intermediate positions are also possible. Alternatively, the valve 14 in the embodiment shown in Fig. 3 upstream of the point at which the

Transmission cooling circuit 19 branches off from the crankcase cooling circuit 1 1 and downstream of the junction in the cylinder head cooling circuit 10 on the one hand and the crankcase cooling circuit 1 1 on the other hand be arranged. Of the

Transmission cooling circuit 19 leads, branching from the crankcase cooling circuit 1 1, to the device 21 for heat absorption from the transmission 20. This device 21 and the transmission 20 have been in the above

Embodiments explained. Downstream of the device 21, the transmission cooling circuit 19, as shown, opens into a connecting line 28 which has an output of the thermal management module 15 with the

Engine cooling circuit upstream of the branch in

Cylinder head cooling circuit 10 and crankcase cooling circuit 1 1 connects. However, it is also possible that the transmission cooling circuit 19

downstream of the device 21 into the thermal management module 15 or directly into the engine cooling circuit downstream of

Thermal management module 15 opens.

Alternatively, the embodiment shown in FIG. 3 may be modified such that the valve 14 is disposed in the crankcase cooling circuit 11 (on the portion thereof separate from the cylinder head cooling circuit 10) downstream of the crankcase water jacket 13 and the transmission cooling circuit 19 downstream of the device 21 in FIGS

Crankcase water jacket 13 opens. Thus, the same effect, as explained above in connection with Fig. 3 or in connection with the preceding embodiments, to achieve, namely, that switching off the crankcase cooling circuit 1 1 by means of the valve 14 automatically shuts off the transmission cooling circuit 19 and a

Turning on the crankcase cooling circuit 1 1 by means of the valve 14th automatically turns on the transmission cooling circuit 19. Different

Cooling fluid flows through the transmission cooling circuit 19 (i.e., it is active) only when the crankcase cooling circuit 11 is also flowed through (i.e., is active) and is independent of whether or not the crankcase cooling circuit 11 is running

Cylinder head cooling circuit 10 is flowed through (i.e., is active).

Further, non-illustrated embodiments of the invention will be described below. Reference is made to the description of the preceding embodiments and only differences:

Thus, the transmission cooling circuit 19, for example, from

Cylinder head cooling circuit 10 between the coolant pump 5 (or the branch) and the cylinder head water jacket 12 branch off. The effect that the transmission cooling circuit 19 is activated depending on the crankcase cooling circuit 1 1, can also be realized in this arrangement by the transmission cooling circuit 19 opens into the crankcase cooling circuit 1 1 and is switched downstream of this junction of the valve 14, as described above.

Likewise, as already mentioned, the coolant pump 5 may be arranged so that a branch in the cylinder head cooling circuit 10 and

Cylinder housing cooling circuit 1 1 downstream of the coolant pump 5 is provided. It would then also be possible to branch off the transmission cooling circuit downstream of the coolant pump 5 and upstream of the branch.

Furthermore, the transmission cooling circuit 19 would not necessarily in the

Cylinder housing water jacket 13 are initiated. Of the

Transmission cooling circuit 19 could also be introduced directly into the thermal management module 15 or into the outlet of the cylinder head water jacket 12. In this case, however, would have the valve 14 with the above be described function provided in the transmission cooling circuit, so that the flow in the transmission cooling circuit 14, ie only the flow in the

Transmission cooling circuit, as described above can be switched.

It has been described above that the engine cooling circuit has a

Cylinder head cooling circuit 10 and a crankcase cooling circuit 1 1, wherein over a certain portion of the

Cylinder head cooling circuit 10 and the crankcase cooling circuit 1 1 run together, then be divided over a respective

Section separated from each other and then be merged again. However, the invention is not limited thereto and the two cooling circuits 10 and 11 could also be completely separate.

In the embodiment shown in Fig. 1 of the runs

Engine oil cooling circuit 1 6 branching off from the crankcase cooling circuit 1 1 to the point 18 in the crankcase, i. in a channel formed in the crankcase material. Likewise, the transmission cooling circuit 19 extends from the crankcase cooling circuit 1 1 branches off until

Engine oil water heat exchanger 17 in the crankcase. This

However, embodiment is not limited thereto, and said portions extending in the crankcase can also outside the

Crankcase run, as is the case for example in Fig. 3.

In the embodiment shown in Fig. 2 of the runs

Engine oil cooling circuit 1 6 and the transmission cooling circuit 19 together from the crankcase cooling circuit 1 1 branches off to a point downstream of the engine oil heat exchanger 17 and upstream of the

Check valve 22 in the crankcase, i. in an im

Crankcase material formed channel. However, this embodiment is not limited to this and the said crankcase extending portions may also extend outside of the crankcase, as is the case for example in Fig. 3. In the embodiment shown in Fig. 3 of the runs

Transmission cooling circuit 19 from the valve 14 and the crankcase cooling circuit 1 1 branches off to the device 21 outside the crankcase, i. outside the crankcase material. However, this embodiment is not limited thereto and the said portion of

Transmission cooling circuit 19 can also at least partially in the

Crankcase, i. in a passageway formed in the crankcase material.

In addition, the invention according to one embodiment discloses a control method for a refrigerant circuit 1 with a

Engine cooling circuit 10, 1 1 in the coolant for cooling a

Internal combustion engine 6, 8 is circulated; a transmission cooling circuit 19 for cooling a transmission 20, which branches off from the engine cooling circuit 10, 1 1; a valve 14, which is arranged in the transmission cooling circuit 19, wherein the valve 14 is opened and closed depending on an operating condition of the engine and / or the transmission.

According to another embodiment, the valve 14 is opened and closed depending on engine speed and / or engine torque.

According to a further embodiment, the valve 14 is only above a certain threshold of the engine speed and / or the

Engine torque opened.

While the invention in detail in the drawings and the

While the foregoing description and description has been presented and described, this illustration and description is to be considered as illustrative or exemplary, and not restrictive, and it is not intended that the invention be limited to the disclosed embodiments restrict. The mere fact that certain features are in

various dependent claims should not indicate that a combination of these features could not be used to advantage.

Claims

claims

1 . Coolant circuit (1) with

an engine cooling circuit (10, 11) in the coolant for cooling an internal combustion engine (6, 8) is circulated;

a transmission cooling circuit (19) for cooling a transmission (20), which branches off from the engine cooling circuit (10, 1 1);

a valve (14) which is arranged in the transmission cooling circuit (19), and

a controller (26) adapted to open and close the valve (14) depending on an operating condition of the internal combustion engine and / or the transmission.

2. Coolant circuit (1) according to claim 1, wherein the

Engine cooling circuit (10, 1 1) comprises a cylinder head cooling circuit (10) and, separately, a crankcase cooling circuit (1 1), wherein the

Transmission cooling circuit (19) on a section along which the

Crankcase cooling circuit (1 1) is separated from the cylinder head cooling circuit (10), branches off from the crankcase cooling circuit (1 1).

3. coolant circuit (1) according to claim 2, wherein

the crankcase cooling circuit (1 1) a

Crankcase water jacket (13) which is guided around cylinder bores (7), and

the transmission cooling circuit (19) opens downstream of a device (21) for absorbing heat from the transmission (20) in the crankcase water jacket (13).

4. The coolant circuit (1) according to claim 3, wherein the valve (14) is located downstream of the crankcase water jacket (13).

5. The coolant circuit (1) according to claim 4, wherein downstream of the valve (14) of the cylinder head cooling circuit (10) and the

Crankcase cooling circuit (1 1) are brought together again.

6. coolant circuit (1) according to one of claims 2 to 5, wherein the engine cooling circuit (10, 1 1) at a branch in the

Cylinder head cooling circuit (10) and the crankcase cooling circuit (1 1) branches, wherein the transmission cooling circuit (19) downstream of the

Branching branches off the crankcase cooling circuit (1 1).

7. coolant circuit (1) according to claim 6, wherein the

Transmission cooling circuit (19) downstream of the branch and upstream of a crankcase water jacket (13) of the crankcase cooling circuit (1 1) branches off from the crankcase cooling circuit (1 1).

8. The coolant circuit (1) according to claim 6 or 7, wherein the crankcase cooling circuit (1 1) downstream of the branch into a crankcase water jacket (13) and a motor oil cooling circuit (16) which is adapted to cool a motor oil via a heat exchanger (17) Branched, and wherein the transmission cooling circuit (19) of the

Engine oil cooling circuit (1 6) branches off.

9. coolant circuit (1) according to one of the preceding claims, wherein in the transmission cooling circuit (1 6) a check valve (22)

is provided.

10. coolant circuit (1) according to one of claims 6 to 7, wherein the branching of a coolant pump (5) is formed.

1 1. Coolant circuit (1) according to one of the preceding claims, wherein the controller (26) is adapted, the valve (14) depending on a Engine speed and / or a motor torque to open and close.

12. The coolant circuit (1) according to claim 1 1, wherein the controller (26) is adapted to open the valve (14) only above a certain threshold of the engine speed and / or the engine torque.

13. Motor vehicle with a coolant circuit according to one of the preceding claims.