EP2427638A1

EP2427638A1 - Coolant circuit

Info

Publication number: EP2427638A1
Application number: EP10719914A
Authority: EP
Inventors: Steffen Triebe; Dieter Lachner; Stefan Rank; Stephan Adam
Original assignee: Audi AG
Current assignee: Audi AG
Priority date: 2009-05-06
Filing date: 2010-05-04
Publication date: 2012-03-14
Also published as: CN102414415B; DE102009020187B4; KR20120024535A; JP2012526225A; US8757110B2; CN102414415A; KR101419104B1; DE102009020187A1; WO2010127826A1; JP5323255B2; US20120048217A1

Abstract

A coolant circuit, particularly a coolant circuit comprising a plurality of partial circuits 1, 2 and 3 of an internal combustion engine 11 having a main coolant circuit 1 and a heating circuit 2, and a coolant delivery pump 5 disposed at a rotating actuator 4, wherein the rotating actuator 4 comprises a rotary slide housing 20 having a plurality of connections 8a, 8b, 9a, 9b, 10a through which a coolant can flow, and a first and at least one second rotary slide 6 and 7 which is rotatably mounted in the rotary slide housing 20 and has at least one rotary slide flow opening 8, 9, 10 forming a flow path, and wherein the connections 8a, 8b, 9a, 9b, 10a can be brought into an at least partial overlap with the rotary slide openings 8, 9, 10 by a rotating movement of the respective rotary slide 6 and/or 7, wherein a first branch 1a of the main coolant circuit 1, which leads from the internal combustion engine 11 via a main cooler 12 to the main cooler connection 8b of the first rotary slide, can be controlled by the first rotary slide 6, and a second branch 1b of the main coolant circuit 1, which leads from an outlet 21 of the coolant delivery pump 5 to the internal combustion engine 11, can be controlled by the second rotary slide 7.

Description

Coolant circuit

A plurality of partial circuits comprising coolant circuit of an internal combustion engine for a motor vehicle with a device for operating such a coolant circuit, in particular for controlling the coolant flow in the individual subcircuits.

Such coolant circuits are preferably used for the thermal management of an internal combustion engine, wherein the coolant flow between the sub-circuits of the coolant circuit is distributed by a device for operating the coolant circuit such that adjusts an optimum operating temperature of the internal combustion engine as quickly as possible.

DE 602 09 019 T2 shows a control valve for a cooling circuit of an internal combustion engine, wherein the circuit is traversed by a coolant and a first branch with a radiator of the engine, a second branch forming a branch line of the radiator, and one or more third branches with each having at least one hot air generator for heating the passenger compartment. The control valve is formed as a body having a fluid inlet, a second branch connected to the first output, a second branch connected to the first branch and at least one second branch connected to the third branch, wherein a rotatably disposed within the body regulating member of the selective Control of the outputs is used. By the rotation of the Regulierorgans in a given direction, a defined sequence of positions can be traversed. It is in a first position with the In a second position, in addition to the second output, the second output connected to the first branch is opened, in a third position, only the second output is opened, in a fourth position, the second and the third branch are connected third output open, in a fifth position, all outputs are open, in a sixth position, the first and the third output are open and in a seventh position, the first or third output is open. Furthermore, the regulating member can also assume a position in which no output is opened.

However, a disadvantage of such a control valve is the rigidly predetermined sequence of possible positions. Thus, with changing coolant requirements in the individual circuits frequent position changes are necessary, which require just as frequent rotation of Regulierorgans. The fact that the control valve realizes many functions with only one Regulierorgan, a complex structure of the control valve with a variety of components is necessary, which brings difficulties in wear and tightness with it.

DE 103 06 094 A1 shows an internal combustion engine cooling system for a vehicle having a coolant pump, an engine circuit for conducting the coolant through the engine, a radiator circuit for conducting the coolant through the radiator, a bypass circuit for returning the coolant to the engine circuit without flowing through the radiator circuit, and a heater circuit for conducting the coolant through the heater core. For switching the coolant, a rotary valve is described with a valve body having an inlet port and a plurality of outlet ports, wherein the outlet ports a radiator port for conducting the coolant in a radiator circuit, a bypass port for conducting the coolant in a bypass circuit and a heater port to Conducting the coolant in a Heizerkreislauf include. The valve body further includes a rotatably mounted Stromverzweiger with a plurality of fluid passages, which depend on a rotational position of Power splitter for preset flow paths between the inlet port and the outlet ports. The preset flow paths thereby comprise a first mode of operation for distributing the coolant to the radiator connection and to the heater connection while blocking the bypass connection, a second mode of distributing the coolant to the bypass connection while simultaneously blocking the coolant from the radiator connection and the heater connection, a third mode of operation Distributing the coolant to the heater port while simultaneously blocking the coolant from the radiator port and the bypass port, and a fourth mode of distributing the coolant to the radiator port and the bypass port while blocking the coolant from the heater port.

A disadvantage of such a combustion engine cooling system is due to the structure of the rotary valve limiting the switchable circuits. The inclusion of additional circuits would inevitably lead to a deterioration in the control of the circuits in detail. As a result, the coolant temperature can not be adjusted with sufficient accuracy and speed to the desired value, which leads to a poorer achievement of the operating temperature of the internal combustion engine.

The object of the present invention is therefore to provide a coolant circuit which, with a simple construction, permits extensive control of a multiplicity of partial circuits of the coolant circuit.

This object is solved by the features of patent claim 1.

A coolant circuit, in particular a multi-circuit having coolant circuit of an internal combustion engine with a main cooling circuit and a heating circuit, has a arranged on a turntable coolant pump, wherein the turntable with a rotary valve housing a plurality of flowed through by coolant connections, and a first and at least a second rotatably mounted in the rotary valve housing rotary valve, each having at least one flow path forming rotary valve flow-through, the connections brought by a rotational movement of the respective rotary valve in at least partially overlap with the rotary valve flow openings and wherein a first branch of the main cooling circuit leading from the internal combustion engine to a main radiator port of the first rotary valve is switchable by the first rotary valve, and wherein a second branch of the main cooling circuit leading from an outlet of the coolant supply pump to the internal combustion engine is switchable by the second rotary valve

By switching the two branches of the main cooling circuit of different rotary valves, it is possible to control a plurality of sub-circuits of the coolant circuit. The headers of the individual subcircuits are connected to the first rotary valve, which is fluidically connected to a suction port of the coolant pump. By rotating the first rotary valve relative to the rotary valve housing, the rotary valve flow-through openings of the first rotary valve can be brought into a continuously variable overlap with the corresponding connections of the rotary valve housing and thus switch different flow paths with varying flow rates. The control of the return flow of the coolant from the coolant supply pump is realized in a second branch of the main cooling circuit by the second rotary valve. Regardless of the current position of the first rotary valve, a coolant flow from the coolant supply pump to the internal combustion engine can thereby be variably opened or closed continuously. The second rotary valve can be very easily formed as a rotary body with a through hole as a rotary valve flow-through, which corresponds to the two opposite ports of the rotary valve housing. Through this very simple design of the turntable relatively many subcircuits can be controlled inexpensively and accurately.

In a preferred embodiment, the heating circuit branches off upstream of the second rotary valve from the second branch of the main cooling circuit and leads coolant via a heating heat exchanger to the internal combustion engine. By the heating circuit branches off in front of the second rotary valve, this is constantly acted upon regardless of the position of the second rotary valve with heated coolant from the coolant pump, which contributes to a rapid heating of the passenger compartment in the motor vehicle through the heater core.

In a preferred embodiment, a bypass branches off from the first branch of the main cooling circuit downstream of the internal combustion engine to a bypass port of the first rotary valve, wherein the first rotary valve switches the bypass. Through the bypass heated coolant flows from the internal combustion engine to the bypass port of the first rotary valve, without being cooled by the main radiator. Thus, at the first rotary valve, elevated-temperature coolant from the bypass and lower-temperature coolant from the main cooler of the first branch of the main cooling circuit are available, which can be mixed by rotating the first rotary valve in any mixing ratio.

In a preferred embodiment, an oil cooler circuit carries coolant from the engine via an oil cooler to an oil cooler port of the first rotary valve, wherein the first rotary valve switches the oil cooler circuit. Through the oil cooler circuit heated coolant flows from the internal combustion engine into the oil cooler, where a heat exchange with the lubricant of the internal combustion engine takes place. From the oil cooler, the coolant flows to the oil cooler port of the first rotary valve, where it can be mixed with the coolant flows from the other sub-circuits.

In a preferred embodiment, after the start of the internal combustion engine and / or below a first threshold value of the coolant temperature, the second rotary valve closes the second branch of the main cooling circuit. If the coolant has a relatively low temperature below a first threshold, which is often the case after the start of the engine, the second branch of the main cooling circuit is closed by the second rotary valve, whereby no coolant from the coolant supply pump can flow back into the internal combustion engine. If the heating circuit is also closed, the coolant heats up particularly quickly in the internal combustion engine, since no circulation takes place in the coolant circuit. Preferably, in this phase, the first rotary valve closes the oil cooler port and the main radiator port while the bypass port is opened. Thus, all coolers located in the coolant circuit are not flowed through with coolant during this phase.

In a preferred embodiment, between the first threshold value of the coolant temperature and a second threshold value of the coolant temperature, the first rotary valve opens the bypass and the second rotary valve opens and closes the second branch of the main cooling circuit at intervals. As soon as the coolant temperature rises above the first threshold value but is still below a second threshold value, the second rotary valve is rotated in such a way that it passes coolant through at intervals. This results in a relatively low coolant flow with a weak circulation of the coolant within the internal combustion engine, which leads to a more homogeneous temperature distribution at the individual components of the internal combustion engine at a further rapid heating rate of the coolant. Preferably, in this phase, the first rotary valve closes the oil cooler port and the main radiator port while the bypass port is opened. In a preferred embodiment, between the second threshold value of the coolant temperature and a third threshold value of the coolant temperature, the first rotary valve opens the bypass and the oil cooler circuit and the second rotary valve opens the second branch of the main cooling circuit. As soon as the coolant temperature rises above the second threshold value but is still below a third threshold value, the second rotary valve is permanently opened. In this phase, the first rotary valve opens the oil cooler connection in addition to the bypass connection, but preferably still keeps the main cooler connection closed. As a result, heated coolant from the internal combustion engine in the oil cooler deliver a portion of its heat to the lubricant, causing it to heat up faster.

In a preferred embodiment, between the third threshold of coolant temperature and a coolant temperature limit, the first rotary valve opens the oil cooler circuit and intermittently opens and closes the first branch of the main cooling circuit and the bypass to achieve a coolant temperature set point and the second rotary valve opens the second branch of the main cooling circuit. As soon as the coolant temperature rises above the third threshold value, but is still below a limit value, the coolant has reached approximately its intended setpoint temperature, whereupon the first rotary valve alternately alternately opens and closes the bypass connection and the main radiator connection. Thereby, a desired mixing ratio between the two coolant streams with different temperature level for maintaining the target temperature can be achieved.

In a preferred embodiment, the coolant temperature in the first branch of the main cooling circuit is determined downstream of the internal combustion engine. By determining the coolant temperature in the first branch of the main cooling circuit at the coolant outlet of the internal combustion engine can be relatively simple be closed on the present in the internal combustion engine coolant temperature.

In a preferred embodiment, in a coasting operation after the engine is shut down, the first rotary valve opens the first branch of the main cooling circuit and closes the bypass, and the second rotary valve closes the second branch of the main cooling circuit. Since in after-running operation after switching off the internal combustion engine by the lack of wind usually no sufficient heat dissipation takes place on the radiators more, the second rotary valve closes the second branch of the main cooling circuit, while the first rotary valve opens the main radiator connection and the bypass port, and the oil cooler connection closes. As a result, the coolant from the internal combustion engine can flow back into the internal combustion engine via the main radiator, the turntable and the heating heat exchanger. By flowing through both the main radiator and the heating heat exchanger, the cooling surface increases, which contributes to improved heat dissipation.

In a preferred embodiment, during the follow-up operation, a heating feed pump arranged in the heating circuit circulates the coolant. Since from a belt-driven coolant delivery pump after switching off the engine no more capacity can be retrieved, the circulation takes place during the follow-up operation by an electrically driven heating pump in the heating circuit.

In a preferred embodiment, a shut-off valve is arranged in the heating circuit, in particular upstream of the heating pump, which is open in the wake mode. By the shut-off valve, the inflow of coolant to the heater core can be interrupted when no heating power for the passenger compartment of the motor vehicle is required. In a preferred embodiment, the first rotary valve is arranged coaxially to the suction mouth of the coolant delivery pump and the second rotary valve is arranged axially parallel to the suction mouth of the coolant delivery pump. By the first rotary valve is arranged with its axis of rotation coaxial with the axis of rotation of the suction mouth of the coolant delivery pump, the coolant delivery pump can easily suck the coolant from the interior of the first rotary valve. The second rotary valve is arranged with its axis of rotation axially parallel to the axis of rotation of the suction mouth of the coolant pump with a fluidic connection to the outlet of the coolant pump, so that the coolant pump can promote the sucked from the first rotary valve coolant to the second rotary valve. Particularly advantageous is an arrangement of the second rotary valve in a radial peripheral region of the coolant supply pump. Such an arrangement provides advantages in terms of space utilization.

In a preferred embodiment, the first rotary valve is driven by an actuator and the second rotary valve is operatively connected via at least one angular range with the first rotary valve, wherein the second rotary valve is driven by the first rotary valve. By only the first rotary valve is provided with an actuator, costs and space can be saved. The drive of the second rotary valve takes place indirectly by a toothing with the first rotary valve, wherein the first and the second rotary valve mesh with each other only in an angular range.

In a preferred embodiment, the angular range of attacks is limited, where the second rotary valve comes to rest, if it is not operatively connected to the first rotary valve. If there is no more active connection between the first and the second rotary valve, the second rotary valve is located on one of the stops on the outer edge of the angle rich, while the first rotary valve outside the angle range can continue to turn.

Further details, features and advantages of the invention will become apparent from the following description of a preferred embodiment with reference to the drawings.

Show:

1 shows an overview of a coolant circuit with a device for operating the coolant circuit.

Fig. 2 is a sectional view of a turntable;

Fig. 3 is a sectional view of a turntable;

Fig. 4 is an illustration of the adjustable by the overlap of the connections with the rotary valve flow openings flow cross sections.

1, a coolant circuit for an internal combustion engine 11, a main cooling circuit 1, a heating circuit 2, an oil cooler circuit 3 and a turntable 4 for controlling the coolant flows in the individual subcircuits 1, 2 and 3. The turntable 4 consists of a rotary valve housing with a first and a second rotatably mounted rotary valve 6 and 7, the rotary valve flow-through openings 8, 9 and 10 have. The rotary valve housing has in its wall a plurality of coolant flows through connections, which can be brought by rotation of the rotary valve 6 and / or 7 in at least partially overlapping with the rotary valve flow openings 8, 9 and / or 10 and so different flow paths for the connected subcircuits 1, 2 and 3 form. At the turntable 4 is a Kühlmittelför- arranged 5, the coolant from the first rotary valve 6 sucks and promotes the second rotary valve 7. The internal combustion engine 11 consists essentially of a cylinder block and a cylinder head, which are flowed through by coolant, whereby the amount of heat released during the combustion process in the cylinders of the internal combustion engine 11 is partially transferred to the coolant. From the internal combustion engine 11, a first branch 1a of the main cooling circuit 1, the heated coolant via a main cooler 12, which cools the coolant, to a main radiator port in the rotary valve housing, which is fluidly connectable to the rotary valve flow-through 8 of the first rotary valve 6. Upstream of the main cooler 12, a bypass 15 branches off from the first branch 1a of the main cooling circuit 1 to a bypass port of the first rotary valve 6, which is fluidically connectable to the rotary valve throughflow 8 of the first rotary valve 6. By a rotational movement of the first rotary valve 6, the rotary valve through-flow opening 8 can be brought into at least partially overlap with the bypass connection and / or the main radiator connection and thus open or close the two flow paths of the internal combustion engine 11 to the coolant delivery pump 5 continuously variable. From the outlet of the coolant supply pump 5, a second branch 1 b of the main cooling circuit 1 via the second rotary valve 7 leads to the internal combustion engine 11. The second rotary valve 7 has a rotary valve flow-through 9, with the connections of the second rotary valve 7 in the rotary valve housing by a rotational movement of the second Rotary slide 7 can be brought into at least partially overlap and so a flow path from the coolant supply pump 5 to the engine 11 is infinitely variable opens or closes. Upstream of the second rotary valve 7, the heating circuit 2 branches off from the second branch 1b of the main cooling circuit 1 and leads coolant from the coolant supply pump 5 via a shut-off valve 17, a heating pump 16 and a heat exchanger 13 to the engine 11. The check valve 17 is closed when no heating power is requested and the heating feed pump 16 is preferably electrically driven to circulate the coolant through the refrigerant circuit when the flow rate of the coolant supply pump 5 is too low. From the internal combustion engine 11, furthermore, an oil cooler circuit 3 conducts coolant via the oil cooler 14 to an oil cooler connection in the rotary valve housing. The first rotary valve 6 has a further rotary valve flow-through opening 9 which can be brought into at least partial overlap with the oil cooler connection and thus opens or closes a flow path from the internal combustion engine 11 to the coolant supply pump 5 in an infinitely variable manner. The oil cooler 14 serves to control the temperature of the lubricant of the internal combustion engine 11.

2, a turntable 4 is arranged on the outer wall of the internal combustion engine 11 and comprises a rotary valve housing 20 with a first and a second rotatably mounted rotary valve 6 and 7, which are preferably designed as a rotary body with an internal volume. The walls of the rotary valve 6 and 7 have rotary valve through-flow openings 8, 9 and 10, through which the rotary valve 6 and 7 can be acted upon with coolant. At the first rotary valve 6, a preferably belt-driven coolant delivery pump 5 is arranged, which communicates with its suction port 18 fluidly connected to the first rotary valve 6 and communicates with its outlet 21 fluidly with the second rotary valve 7 in connection. The first rotary valve 6 is directly driven by an actuator 19 via a rotation axis, while the second rotary valve 7 is driven by the first rotary valve 6. On the rotary valve housing 20 a plurality of terminals 8a, 8b, 9a, 9b and 10a are mounted, which can be flowed through by coolant. By a rotational movement of the first rotary valve 6 and / or the second rotary valve 7, the terminals 8a, 8b, 9a, 9b and / or 10a can be brought into at least partial overlap with the corresponding rotary valve through-flow openings 8, 9 and / or 10 and thus continuously variably open and close different flow paths. The rotary slide through-flow opening 8 of the first rotary valve 6 is a bypass port 8a, which can be acted upon by coolant from a bypass 15, and a main radiator port 8b, which can be acted upon by coolant from a first branch 1a of the main cooling circuit assigned. The further rotary valve flow-through opening 10 of the first rotary valve 6 is associated with an oil cooler connection 10 a, which can be acted upon by coolant from an oil cooler circuit 3. The rotary valve throughflow opening 9 of the second rotary valve 7 is associated with two opposing ports 9a and 9b, which are positioned around the second rotary valve so that there is always a uniform overlap of the two ports 9a and 9b with the rotary valve flow-through 9. The second rotary valve 7 switches the second branch 1b of the main cooling circuit, which leads from the outlet 21 of the Kühlmittelförderpurhpe 5 to the internal combustion engine 11 and branches off from the upstream of the second rotary valve 7 of the heating circuit 2.

According to Fig. 3, a turntable 4 has a rotary valve housing 20 in which a first rotary valve 6 and a second rotary valve 7 are rotatably mounted, wherein the first rotary valve 6 is driven directly and the second rotary valve 7 over a defined angular range by a gear 22 with the first rotary valve 6 is operatively connected and is driven by this. The second rotary valve 7 has a rotary valve flow-through opening 9, which can be brought to at least partially overlap with the arranged on both sides of the second rotary valve 7 terminals 9a and 9b and thus a flow path continuously variable opens or closes. In this case, coolant flows out of the internal combustion engine via the first branch 1 a of the main cooling circuit through the first rotary valve 6 and is conveyed by a coolant pump in front of the second rotary valve 7. Depending on the position of the second rotary valve 7 relative to the terminals 9a and 9b, the coolant can pass the second rotary valve 7 and flow back to the internal combustion engine in a second branch 1b of the main cooling circuit. According to FIG. 4, radially distributed rotary vane throughflow openings 8, 9 and 10 are arranged on the first and the second rotary vane. By a rotational movement of the first and / or the second rotary valve, connections 8a, 8b, 9a, 9b and 10a fixedly arranged on a rotary valve housing can be brought into at least partial overlap with the associated rotary valve through-flow openings 8, 9 and / or 10. It should be noted that the terminals 9a and 9b are arranged on the second rotary valve, that a rotation of the same leads to a uniform overlap of the two ports 9a and 9b with the rotary valve flow-through 9. The second rotary valve can be moved together with the first rotary valve over an angular range α, which is preferably between 90 ° and 160 ° rotation. The first rotary valve can move beyond the angular range α from an initial position at 0 ° to an end position at approximately 260 °, the second rotary valve abutting a left or right stop at the outer limits of the angular range α when the first The rotary valve does not cover the angular range α. After the start of the internal combustion engine and below a first threshold value of the coolant temperature, the first and the second rotary valve are operatively connected, the first rotary valve passing coolant from the bypass port 8a and the second rotary valve abutting the right stop of the angular range α, where it does not pass coolant. After exceeding the first threshold value and below a second threshold value of the coolant temperature, the second rotary valve moves together with the first rotary valve from the right stop of the angular range α and intermittently directs coolant from the bypass port 8a via the first rotary valve through the ports 9a and 9b of the second rotary valve. After exceeding the second threshold and below a third threshold value of the coolant temperature, the second rotary valve is brought to rest against the left stop of the angular range α, whereby the ports 9a and 9b of the second rotary valve is fully opened. In Coolant from the oil cooler port 10a and the bypass port 8a flows in the first rotary valve. After exceeding the third threshold and below a limit value of the coolant temperature, the first rotary valve moves further in the direction of the initial position, while the second rotary valve continues to abut the left stop of the angular range α. Coolant from the oil cooler connection 10a constantly flows into the first rotary valve, wherein a defined mixing ratio of coolant from the bypass port 8a and coolant from the main radiator port 8b can be adjusted by a continuous displacement of the first rotary valve until a desired temperature of the coolant is reached , In a follow-up operation after switching off the internal combustion engine, the first rotary valve shifts the second rotary valve to the right stop of the angular range α, so that no more coolant can flow through the terminals 9a and 9b of the second rotary valve. The first rotary valve rotates further in the direction of the end position, whereby only coolant from the main radiator port 8b is passed through.

List of reference numbers:

1 main cooling circuit

1a first branch (of the main cooling circuit)

1b second branch (of the main cooling circuit)

2 heating circuit

3 oil cooler circuit

4 turntables

5 coolant delivery pump

6 first rotary valve

7 second rotary valve

8 Rotary valve flow-through opening 8a Bypass connection

8b main radiator connection

9 rotary valve flow opening

9a Connection of the second rotary valve

9b Connecting the second rotary valve

10 Rotary valve flow-through opening 10a Oil cooler connection

11 internal combustion engine

12 main coolers

13 heating heat exchanger

14 oil cooler

15 bypass

16 heating pump

17 shut-off valve

18 suction mouth

19 actuator

20 rotary valve housing

21 outlet

22 gear α angle range

Claims

claims

1. coolant circuit, in particular a plurality of partial circuits (1, 2, 3) exhibiting coolant circuit of an internal combustion engine (11) with a main cooling circuit (1) and a heating circuit (2), and one on a turntable (4) arranged coolant conveying pump (5), wherein the rotary actuator (4) has a rotary valve housing (20) with a plurality of connections (8a, 8b, 9a, 9b, 10a) through which coolant can flow, and a first (6) and at least one second rotary valve (7) rotatably mounted in the rotary valve housing (20) each comprising at least one rotary valve through-flow opening (8, 9, 10) forming a flow path, and wherein the connections (8a, 8b, 9a, 9b, 10a) are at least partially overlapped by rotational movement of the respective rotary valve (6, 7) Rotary slide through-flow openings (8, 9, 10) can be brought, characterized in that one of the internal combustion engine (11) via a main radiator (12) to a main radiator connection (8b) of the first rotary valve leading first branch (1a) of the main cooling circuit (1) of the first rotary valve (6) is switchable and that one of an outlet (21) of the coolant pump (5) to the internal combustion engine (11) leading second branch ( 1b) of the main cooling circuit (1) from the second rotary valve (7) is switchable.

2. Coolant circuit according to claim 1, characterized in that the heating circuit (2) branches off upstream of the second rotary valve (7) from the second branch (1b) of the main cooling circuit (1) and coolant via a heating heat exchanger (13) to the internal combustion engine (11) ,

3. coolant circuit according to claim 1 or 2, characterized in that from the first branch (1 a) of the main cooling circuit (1) downstream of the internal combustion engine (11) has a bypass (15) to a bypass port (8 a) of the first rotary valve (6) branches off, wherein the first rotary valve (6) switches the bypass (15).

4. coolant circuit according to one of claims 1 or 3, characterized in that an oil cooler circuit (3) coolant from the internal combustion engine (11) via an oil cooler (14) to a Ölkühleran- circuit (10a) of the first rotary valve (6), wherein the first rotary valve (6) switches the oil cooler circuit (3).

5. coolant circuit according to one of claims 1 to 4, characterized in that after the start of the internal combustion engine (11) and / or below a first threshold value of the coolant temperature of the second rotary valve (7) the second branch (1b) of the main cooling circuit (1) closes ,

6. coolant circuit according to one of claims 1 to 5, characterized in that between the first threshold value of the coolant temperature and a second threshold value of the coolant temperature of the first rotary valve (6) opens the bypass (15) and the second rotary valve (7) the second branch ( 1b) of the main cooling circuit (1) opens and closes at intervals.

7. coolant circuit according to one of claims 1 to 6, characterized in that between the second threshold value of the coolant temperature and a third threshold value of the coolant temperature of the first rotary valve (6) opens the bypass (15) and the oil cooler circuit (3) and the second rotary valve ( 7) opens the second branch (1b) of the main cooling circuit (1).

8. coolant circuit according to one of claims 1 to 7, characterized in that between the third threshold value of the coolant temperature and a limit value of the coolant temperature of the first rotary valve (6) opens the oil cooler circuit (3), and the first branch (1 a) of the main cooling circuit (1 ) and the bypass (15), to achieve a target value of the coolant temperature, opens and closes at intervals and the second rotary valve (7) opens the second branch (1b) of the main cooling circuit (1).

9. coolant circuit according to one of claims 1 to 8, characterized in that the coolant temperature in the first branch (1 a) downstream of the internal combustion engine (11) is determined.

10. coolant circuit according to one of claims 1 to 9, characterized in that in a follow-up operation after switching off the internal combustion engine (11) of the first rotary valve (6) opens the first branch (1a) of the main cooling circuit (1) and the bypass (15) closes and the second rotary valve (7) closes the second branch (1b) of the main cooling circuit (1).

11. Coolant circuit according to one of claims 1 to 10, characterized in that during the follow-up operation in the heating circuit (3) arranged heating pump (16) circulates the coolant.

12. Coolant circuit according to one of claims 1 to 11, characterized in that in the heating circuit (3), in particular upstream of the heating conveyor pump (16), a shut-off valve (17) is arranged, which is open in the afterrunning mode.

13. Coolant circuit according to one of claims 1 to 12, characterized in that the first rotary valve (6) coaxial with the suction mouth

(18) of the coolant supply pump (5) is arranged and the second rotary valve (7) is arranged axially parallel to the suction mouth (18) of the coolant conveying pump (5).

14. Coolant circuit according to one of claims 1 to 13, characterized in that the first rotary valve (6) by an actuator

(19) is drivable and that the second rotary valve (7) over at least one angular range (α) with the first rotary valve (6) is operatively connected, wherein the second rotary valve (7) from the first rotary valve (6) is driven.

15. Coolant circuit according to claim 14, characterized in that the angular range (α) of stops is limited, where the second rotary valve (7) comes to rest when it is not operatively connected to the first rotary valve (6).