DE102009036603A1 - Cooling system for an internal combustion engine - Google Patents

Abstract

The invention relates to a cooling system for an internal combustion engine, in particular of a motor vehicle, comprising a cooling circuit having a guided through a cylinder head of the engine main section and a side section in which a heat exchanger is integrated, which is also involved in an engine oil circuit, wherein the cylinder head for the main portion has a coolant inlet path and a coolant outlet path.
The cold start behavior of the internal combustion engine can be improved if a bypass is provided which connects the Kühlmittelauslasspfad at least one heat exchanger having the coupling portion of the auxiliary portion with the coolant inlet path, wherein a bypass switching means is provided, with which the bypass is activated and deactivated.

Description

The The present invention relates to a cooling system for an internal combustion engine, in particular a motor vehicle.

From the DE 40 327 01 A1 a cooling system is known in which a main cooling circuit is passed through an engine block and a cylinder head and is designed to be deactivated. In addition, an additional cooling circuit or cylinder head circuit is provided, which is passed only through the cylinder head and can be operated independently of the main cooling circuit. In this cylinder head circuit, a coolant-oil heat exchanger may be involved, for example. To bring the engine's lubricating oil quickly to operating temperature.

Other cooling systems for internal combustion engines are from the WO 2005012704 A1 , from the DE 102 12 672 A1 , from the DE 102 41 228 B4 , from the US 7,237,513 B2 and from the DE 100 00 299 A1 known.

The The present invention addresses the problem of for a cooling system of an internal combustion engine a to provide improved embodiment, in particular Characterized in that during a cold start or during a Warm-up phase of the internal combustion engine, in particular the lubricating oil the internal combustion engine, as soon as possible to operating temperature can be brought without a complicated Intervention in the construction of the internal combustion engine or its engine block or cylinder head is required.

According to the invention this problem by the subject-matter of the independent claim solved. Advantageous embodiments are the subject the dependent claims.

The Invention is based on the general idea of having a controllable, So provide activatable and deactivatable bypass, it allows at least one engine oil heat exchanger having Coupling area of the auxiliary section on the one hand with a cylinder head the internal combustion engine extending Kühlmittelauslasspfad and on the other hand with a in the cylinder head of the internal combustion engine to connect extending coolant inlet path. For controlling the bypass may be provided with a bypass switching device with which bypass can be activated and deactivated. Preferably the bypass is connected to a heating fluid circuit. This allows an already existing coolant circuit be used in the internal combustion engine, anyway to a in the cylinder head of the engine extending Kühlmittelauslasspfad connected. This construction makes it possible, for example with the cooling circuit deactivated, that is during one Cold starts, the cylinder head directly above the coolant outlet Heat to escape, so that over the coupling part of the minor section and the engine oil heat exchanger incorporated therein the engine lubricating oil at a very early date heat. As a result, the engine oil is comparatively quickly brought to its operating temperature, reducing engine lubrication improves and the emission levels and fuel consumption of the internal combustion engine can be improved.

Especially it is also possible in this embodiment of the cooling system in a cooling circuit guided through the cylinder head, which can be activated and deactivated by means of a thermostatic valve is to make the bypass so that bypasses the thermostatic valve, at least when the cooling circuit is deactivated Continue to operate coupling area of the auxiliary section. On this way it is particularly easy and with little intervention in the construction of a conventional cooling system possible, for a cold start of the engine the (big) Disable cooling circuit with the aid of the thermostatic valve so that the heat generated in the cylinders the cylinder head can heat up without losing the coolant of the entire cooling circuit to heat up. By activating the bypass, what For example, by means of a corresponding bypass switching device feasible is, can with the coolant-oil heat exchanger equipped coupling area of the Nebenabschnitts quasi as smaller Cooling circuit operated.

The in the small cooling circuit or in the activated coupling area the secondary section has circulating coolant in the Comparison to the whole or large cooling circuit only a significantly reduced volume and can accordingly at a flow The cylinder head can be heated quickly without it the heating of the cylinder head significantly affected becomes. At the same time can over this small cooling circuit and the incorporated therein heat exchanger in Connection with a coupled engine oil cooling circuit the engine oil comparatively quickly to a viscosity reducing, elevated temperature. hereby The lubricating oil can relatively quickly to a sufficient Operating temperature can be brought, thereby reducing emissions and fuel consumption shortened critical cold start phase can be.

The aforementioned bypass switching device may be integrated into the thermostatic valve according to an advantageous embodiment of the present invention. In principle, however, a construction with a separate additional thermostatic valve is conceivable. Likewise is an elek trisch switchable valve conceivable.

Of the Bypass may contain an auxiliary coolant pump, in addition to a main coolant pump arranged in the main section can be present. This auxiliary coolant pump can be used for the cold start or during a motor warm-up phase activated be in the coupling area of the secondary section or in the small Cooling circuit to promote the coolant. Such an additional coolant pump is particularly then required if the main coolant pump, due to a in cold start or during the warm-up phase closed main thermostatic valve no coolant is circulated or switched off, is mechanically drive-connected with the internal combustion engine and / or if in the coupling area during the bypass operation, ie during of the cold start operation or warm-up phase, a coolant flow direction which is preferably opposite to the coolant flow direction can be oriented in the warm operation of the internal combustion engine prevails in the coupling area. Alternatively, it is also conceivable that anyway existing main coolant pump with a device for To provide a flow direction reversal that allows with constant drive direction of rotation, the conveying direction reverse. Likewise, it is alternatively conceivable, an independent from the internal combustion engine, in particular electrically, drivable coolant pump to be used, which are operated with two conveying directions can and which both promote the coolant in the big main section as well as to the sponsoring of the coolant in the secondary section or in the coupling region can be used.

Corresponding a particularly advantageous embodiment of the Cylinder head contain an additional coolant path, the in addition to the coolant outlet path in the area is arranged by Abgasauslasskanälen and in the previously mentioned side section is involved in the cold start operation forms the small cooling circuit. This way can for the cold start specifically in the area of the exhaust side of the cylinder head Heat absorbed and over the corresponding Transfer heat exchanger to the engine oil become. As a result, the heat transfer on the engine oil can be intensified. The time to reach a sufficient operating temperature for the engine oil can be shortened.

alternative is the additional coolant path as a separate path in the cylinder head trained or is through the existing cooling water jacket by means of a specifically formed longitudinal flow designed in the cylinder head. For the purposes of the invention, it is still conceivable, by means of a specifically formed longitudinal flow along the exhaust outlet in the cylinder head increased To cause heat absorption of the coolant, so that, for example, the heating power of Motorölwärmeübertragers is increased.

Further important features and advantages of the invention will become apparent from the Subclaims, from the drawings and from the associated Description of the figures with reference to the drawings.

It it is understood that the above and the following yet to be explained features not only in each case specified combination, but also in other combinations or can be used in isolation, without the scope of the present To leave invention.

preferred Embodiments of the invention are in the drawings and will become more apparent in the following description explained, wherein the same reference numerals to the same or similar or functionally identical components relate.

It show, in each case schematically,

1 a highly simplified schematic diagram of a cooling system of an internal combustion engine in a first embodiment, during a warm operation of the internal combustion engine,

2 the cooling system off 1 during a cold start of the internal combustion engine,

3 a view like in 1 but in a second embodiment during hot operation,

4 the cooling system off 3 but during the cold start.

According to the 1 to 4 is an internal combustion engine 1 with a partially shown cooling system 2 fitted. The internal combustion engine 1 is preferably in a motor vehicle.

The cooling system 2 includes a cooling circuit 3 , the one main section 44 and a minor section 5 having. The main section 44 is through a cylinder head 4 the internal combustion engine 1 passed through. This cooling circuit 3 Transports a coolant and contains a coolant pump 46 Also used as the main coolant pump 46 or main pump 46 can be designated. This is useful in the main section 44 arranged, in a flow 43 of the main section 44 , Furthermore, in this cooling circuit 3 Usually arranged a coolant-air heat exchanger, which is not shown here and in a vehicle as "Hauptküh ler "is called. This main cooler is usually located upstream of the main pump 46 in the lead 43 of the main section 44 ,

In the secondary section 5 is at least a heat exchanger 6 is involved. This heat exchanger 6 is also in a motor oil circuit 7 involved, in which a motor oil circulates. The engine oil is used to realize lubrication in the internal combustion engine 1 , Furthermore, the cooling circuit includes 3 a thermostatic valve 8th , which is designed so that it depends on a temperature of the cooling circuit 3 or at least the main section 44 or at least the minor section 5 or at least these two sections 5 . 44 can activate and deactivate.

The cylinder head 4 has a coolant inlet path 9 and a coolant outlet path 10 on. The coolant inlet path 9 extends in the range of fresh air intake ducts 11 in the cylinder head 4 to cylinders 12 to lead. The coolant inlet path 9 is inlet side, so via a coolant inlet 13 to the main section 44 or at its forerun 43 connected. On the outlet side, ie at a coolant outlet 14 is the coolant inlet path 9 to the aforementioned subsection 5 connected.

The coolant outlet path 10 extends in the range of exhaust gas outlet channels 15 in the cylinder head 4 are formed and from the cylinders 12 lead away. Further, the coolant outlet path is 10 on the outlet side, ie via a coolant outlet 16 to the main section 44 or at its return 42 connected.

Furthermore, the cylinder head contains 4 several coolant connection paths 17 , each from the coolant inlet path 9 to the coolant outlet path 10 to lead. While the coolant inlet path 9 and the coolant outlet path 10 extend substantially parallel to each other, are the coolant connection paths 17 parallel to each other but to the coolant inlet path 9 and to the coolant outlet path 10 oriented transversely.

Furthermore, the cooling circuit shown here 3 with a bypass 18 equipped with a thermostatic valve 8th bypasses and the coolant outlet path 10 inlet side, so at a coolant inlet 19 with the minor section 5 combines. In other words, a bypass line 20 connects the inlet 19 the coolant outlet path 10 with the minor section 5 , A corresponding connection point of the auxiliary section 5 is there with 21 designated. The aim of the present arrangement is to bypass 18 with a coolant hot side of the cylinder head 4 connect to. Alternatively, accordingly, the bypass 18 with the coolant hot side of the cylinder head 4 over the coolant outlet 16 be connected.

The bypass 18 includes a bypass switching device 22 that is designed to bypass 18 can activate and deactivate. In the example of 1 to 4 is the bypass switching device 22 designed as a valve, in addition to the thermostatic valve 8th is provided. This may be an electrically actuated valve or a thermo-energy-free working thermostatic valve. Alternatively, it is possible to use the bypass switching device 22 in the thermostatic valve 8th to integrate. It is clear that then the connection point 21 on the thermostatic valve 8th is arranged.

Furthermore, the bypass contains 18 here an additional coolant pump 23 , in particular, independent of the internal combustion engine 1 can be operated. For example. is this auxiliary coolant pump 23 or additional pump 23 equipped with an electric motor drive, which is not shown here.

According to a preferred embodiment may be in the bypass 18 also a heat exchanger 24 , For example, a heating heat exchanger, be integrated, which also in an air path 25 is integrated, which serves to supply a room with fresh air and / or with circulating air. For example. can this air path 25 for supplying a vehicle interior, in particular a passenger compartment, with fresh air or circulating air. With a corresponding embodiment of the bypass switching device 22 Can be used in conjunction with an additional bypass line 26 said heat exchanger 24 be activated and deactivated. D. h., If during the warm-up phase no heating demand for the passenger compartment is needed, by means of the bypass switching device 22 the additional bypass line 26 disabled and the bypass line 20 activated. Here is the heat exchanger 24 with coolant does not flow through. The coolant only passes through the bypass line 20 to the secondary section 5 , so that a rapid heating of the ancillaries or the Motorölwärmeübertragers 6 done without heat to the passenger compartment heating. A decoupling of the heat exchanger 24 takes place.

In the embodiments shown here, the minor section contains 5 in addition to the engine oil heat exchanger 6 at least one other heat exchanger. In the example, there are two more heat exchangers 27 and 28 intended. It is clear that in principle more than two such additional heat exchangers 27 . 28 can be provided. Visible are these other heat exchangers 27 . 28 to the engine oil heat exchanger 6 arranged in parallel, what they in corresponding parallel lines 29 respectively. 30 are arranged. In these parallel lines 29 . 30 can switch valves 31 respectively. 32 be arranged to the extra heat transfer ger 27 . 28 to be able to activate and deactivate independently of demand and independently of each other.

These switching valves 31 . 32 can be electrically operated. In principle, a design as a thermostatic valves is conceivable. The other heat exchangers 27 . 28 can be used, for example, to a transmission oil and / or a coolant from the exhaust gas turbocharger or generator of the internal combustion engine 1 tempered motor vehicle.

In the in the 3 and 4 The embodiment shown is the cylinder head 4 additionally with an additional coolant path 33 fitted. This auxiliary coolant path 33 extends in the cylinder head 4 in addition to the coolant outlet path 10 in the area of the exhaust outlet ducts 15 , Further, this auxiliary coolant path is 33 in the secondary section 5 involved. These are on the cylinder head 4 another inlet 34 and another outlet 35 intended. The coolant outlet path 10 is now expedient on the inlet side, ie via its inlet 19 with the auxiliary coolant path 33 connected. This is done in the example via a connecting line 36 that the inlet 19 the coolant outlet path 10 with the outlet 35 of the auxiliary coolant path 33 combines. It is clear that such a connection 36 also internally, ie within the cylinder head 4 is feasible. Furthermore, there is the coolant inlet path 9 on the outlet side, ie via its outlet 14 with this additional coolant path 33 in connection. For this leads a line section 37 of the cooling circuit section 5 from the outlet 14 the coolant inlet path 9 to a branching point 38 , from which a line section 39 to the inlet 34 of the auxiliary coolant path 33 leads while a line section 40 to the engine oil heat exchanger 6 and to the optionally present at least one heat exchanger 27 . 28 or to the parallel lines 29 . 30 leads.

The in the 1 and 2 The embodiment shown operates as follows:
During a warm operation of the internal combustion engine 1 turns the in 1 shown state. Here is the cooling circuit 3 active while bypassing 18 depending on heating demand is active or inactive. This is the thermostatic valve 8th opened, the coolant flows in the main section 44 on the one hand via the coolant inlet path 9 in the cylinder head 4 on, over the connection paths 17 to the coolant outlet path 10 and via the coolant outlet path 10 from the cylinder head 4 out. On the other hand, a part of the coolant flows in parallel through the secondary section 5 because part of the coolant is from the coolant inlet path 9 over its outlet 14 to the secondary section 5 arrives. Overall, this is a large cooling circuit active, the main section 44 and the minor section 5 includes. This large cooling circuit allows the desired cooling of the cylinder head 4 and engine oil and other equipment. In addition, by a connection of the bypass 18 arranged heat exchanger 24 an interior heating can be performed.

2 shows a state of the cooling system 2 , who is looking for a cold start of the internal combustion engine 1 can be set. During this cold start or during a warm-up phase, the large cooling circuit is closed by closing the thermostat 8th or by deactivating the main pump inactive. That's the bypass 18 activated, allowing coolant from the inlet 19 the coolant outlet path 10 through the side section 5 to the outlet of the coolant inlet path 9 can flow. Visible is the flow direction in the secondary section 5 during the cold start thus opposite to the flow direction in the secondary section 5 during hot operation. During the cold start, the coolant thus flows through the outlet 14 in the coolant inlet path 9 on, passes over the connection paths 17 to the coolant outlet path 10 and gets there over the inlet 19 back to the secondary section 5 , The secondary section 5 forms together with the bypass 18 thereby a small cooling circuit with compared to the large cooling circuit significantly reduced coolant volume. Depending on the heating requirement is by means of the bypass switching device 22 the bypass line 26 mitaktiviert or deactivated. If the heater is not needed, then the coolant flows to the secondary section 5 only via the bypass line 20 , Accordingly, no heat is transferred to the heat exchanger 24 , In this case, the coolant circulates only via at least one heat exchanger 7 . 27 respectively. 28 the ancillaries and the cylinder head 4 ,

For the realization of the small cooling circuit, the at least one heat exchanger 6 containing coupling region 45 of the secondary section 5 as well as the bypass 18 and the cylinder head 4 includes, the auxiliary pump 23 to be activated. The bypass switching device 22 is in the example of 2 switched so that the coolant the two bypass lines 20 and 26 flows through in parallel, so that a heat transfer to the air flow 25 is possible. In any case, however, a heat transfer to the oil circuit 7 realized to as quickly as possible during the cold start and as much heat to the lubricating oil of the internal combustion engine 1 to be able to transfer. Through the bypass switching device 22 is the bypass line 26 shut off and thus the heat exchanger for the vehicle interior heating decoupled. This is the bypass line 20 more heat output available to the heat exchanger 6 . 27 and 28 can be transferred. In addition, it is optionally possible by appropriate actuation of the switching valves 31 . 32 Preheat other equipment or bring to operating temperature. For example. can by preheating of transmission oil and / or clutch oil, the efficiency in the drive train of the vehicle can be improved.

The in the 3 and 4 The embodiment shown operates as follows:
3 shows the warm operation of the internal combustion engine 1 , Accordingly, the thermostatic valve 8th active or open so that the large cooling circuit is active. In contrast, the bypass 18 inactive. The coolant accordingly flows through the inlet on the one hand 13 in the coolant inlet path 9 , via the connection paths 17 to the coolant outlet path 10 and through the outlet 16 again from the cylinder head 4 out. This allows the cylinder head 4 be cooled intensively. Here, the partial flow branches again. On the one hand flows a part of the coolant over the line section 39 to the inlet 34 of the auxiliary coolant path 33 and thus additionally enters the cylinder head 4 , One in the line section 39 arranged switching valve 47 is closed at this operating point. This coolant passes through the outlet 35 and the connection path 36 to the inlet 19 the coolant outlet path 10 and thus through the cylinder head 4 to the outlet 16 the coolant outlet path 10 , On the other hand, the other coolant partial flow passes over the line section 37 and thereafter through the pipe section 40 at least to the engine oil heat exchanger 26 and parallel to the at least one further heat exchanger 27 . 28 , It is still conceivable, the coolant partial flow to the line section 40 via a bypass line section 37a respectively. The secondary section 5 becomes parallel to the cylinder head 4 flows through with coolant. Optionally, it may also be provided here for heating the air flow 25 usable heat exchanger 24 by a corresponding operation, the bypass switching device 22 to apply coolant.

For realizing the cold start operation, according to this embodiment 4 the thermostatic valve 8th be transferred to its locked position. This deactivates the large cooling circuit. In addition, the bypass will 18 activated. Furthermore, at this operating point in the line section 39 arranged switching valve 47 open. In particular, the auxiliary pump 23 switched on. As a result, the coolant flows in the small cooling circuit, which again the coupling area 45 of the secondary section 5 , the cylinder head 4 as well as the bypass 18 includes. The coolant flows through the inlet 34 in the auxiliary coolant path 33 So in the cylinder head 4 one.

The auxiliary coolant path 33 is alternatively as a separate path in the cylinder head 4 or is formed by the existing water jacket by means of a targeted longitudinal flow in the cylinder head 4 designed.

It emerges from the cylinder head 4 over the outlet 35 of the auxiliary coolant path 33 out. For the purposes of the invention, it is furthermore conceivable, by means of a specifically formed longitudinal flow along the exhaust gas outlet side in the cylinder head 4 To cause increased heat absorption of the coolant, so that the heat output of the heat exchanger 6 . 24 . 27 and 28 is increased.

The auxiliary pump 23 promotes the coolant with appropriate switching position of the bypass switching device 22 parallel through the two bypass lines 20 . 26 , Thus, on the one hand, an admission of the air-coolant heat exchanger takes place 24 , On the other hand, at least the engine oil heat exchanger is pressurized 6 with coolant. Depending on the heating requirement is by means of the bypass switching device 22 the bypass line 26 mitaktiviert or deactivated. If the heater is not needed, then the coolant flows to the secondary section 5 only via the bypass line 20 , Accordingly, no heat is transferred to the heat exchanger 24 , By appropriate actuation of the switching valves 31 . 32 is here also a parallel admission of at least one additional heat exchanger 27 . 28 possible. About the pipe sections 40 . 39 the coolant returns to the cylinder head 4 ,

During this cold start operation are within the auxiliary section 5 , the line section 37 and inside the cooling circuit 3 or within the cylinder head 4 the coolant inlet path 9 and the coolant outlet path 10 deactivated, so essentially does not flow through. Optionally, suitable locking devices for this purpose 41 a flow line 43 of the cooling circuit 3 or in a return line 42 of the cooling circuit 3 be arranged. The proposed configuration, the coolant in the small cooling circuit in a relatively short time can be heated sufficiently far, whereby the engine oil can reach its operating temperature comparatively quickly, which is the fuel consumption of the internal combustion engine 1 reduced during the cold start.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 4032701 A1 [0002]
• - WO 2005012704 A1 [0003]
• DE 10212672 A1 [0003]
• - DE 10241228 B4 [0003]
• - US 7237513 B2 [0003]
• DE 10000299 A1 [0003]

Claims (16)

Cooling system for an internal combustion engine ( 1 ), in particular of a motor vehicle, - with a cooling circuit ( 3 ), one through a cylinder head ( 4 ) of the internal combustion engine ( 1 ) guided through the main section ( 44 ) as well as a secondary section ( 5 ), in which a heat exchanger ( 6 ), which is also incorporated into an engine oil circuit ( 7 ), - the cylinder head ( 4 ) for the main section ( 44 ) a coolant inlet path ( 9 ) and a coolant outlet path ( 10 ), wherein a bypass ( 18 ) is provided, the coolant outlet path ( 10 ) via at least one heat exchanger ( 6 ) having a coupling region ( 45 ) of the minor section ( 5 ) with the coolant inlet path ( 9 ), wherein a bypass switching device ( 22 ) is provided, with which the bypass ( 18 ) can be activated and deactivated. Cooling system according to claim 1, characterized in that during a warm operation of the internal combustion engine, in which the cooling circuit ( 3 ) is active and the bypass ( 18 ) is inactive, coolant from the coolant inlet path ( 9 ) through the cooling circuit section ( 5 ) is guided. Cooling system according to claim 1 or 2, characterized in that during a cold start of the internal combustion engine ( 1 ), in which the cooling circuit ( 3 ) is inactive and the bypass ( 18 ) is active, coolant from the coolant outlet path ( 10 ) through the coupling section ( 45 ) to the coolant inlet path ( 9 ) is guided. Cooling system according to one of claims 1 to 3, characterized in that a thermostatic valve ( 8th ) for activating and deactivating the cooling circuit ( 3 ) is provided, wherein the thermostatic valve ( 8th ) in particular for activating and deactivating the main section ( 44 ) and / or the minor section ( 5 ) can be configured. Cooling system according to claim 4, characterized in that the bypass switching device ( 22 ) into the thermostatic valve ( 8th ) is integrated. Cooling system according to one of claims 1 to 5, characterized in that the bypass ( 18 ) an auxiliary coolant pump ( 23 ), which is for a cold start of the internal combustion engine ( 1 ) is activated. Cooling system according to one of claims 1 to 6, characterized in that in the bypass ( 18 ) a heat exchanger ( 24 ), which is in an air path ( 25 ) for supplying a space, in particular a vehicle interior, is integrated with fresh air and / or circulating air. Cooling system according to one of claims 1 to 7, characterized in that the coolant inlet path ( 9 ) in the range of cylinders ( 12 ) leading fresh gas inlet channels ( 11 ), on the one hand, in particular on the inlet side, to the main section ( 44 ) of the cooling circuit ( 3 ) and on the other hand, in particular on the outlet side, to the secondary section ( 5 ) of the cooling circuit ( 3 ) connected, Cooling system according to one of claims 1 to 8, characterized in that the coolant outlet path ( 10 ) in the region of the cylinders ( 12 ) leading exhaust gas outlet ducts ( 15 ) and, in particular on the outlet side, to the main section ( 44 ) of the cooling circuit ( 3 ) connected, Cooling system according to one of claims 1 to 9, characterized in that the cylinder head ( 4 ) several coolant connection paths ( 17 ) from the coolant inlet path ( 9 ) to the coolant outlet path ( 10 ) to lead. Cooling system according to one of claims 1 to 10, characterized in that the cylinder head ( 4 ) an auxiliary coolant path ( 33 ), which in addition to the coolant outlet path ( 10 ) in the region of the exhaust gas outlet channels ( 15 ) and which is in the secondary section ( 5 ) of the cooling circuit ( 3 ) is involved. Cooling system according to claim 11, characterized in that the coolant outlet path ( 10 ), in particular inlet side, with the additional coolant path ( 33 ) while the coolant inlet path ( 9 ), in particular on the outlet side, with the additional coolant path ( 33 ) connected is. Cooling system according to claim 12, characterized in that during a cold start of the internal combustion engine ( 1 ), in which the cooling circuit ( 3 ) is inactive and the bypass ( 18 ) is active, coolant through the coupling part ( 45 ) of the secondary section ( 5 ) and by the additional coolant path ( 33 ) is guided. Cooling system according to one of claims 1 to 13, characterized in that the secondary section ( 5 ) parallel to the engine oil heat exchanger ( 6 ) at least one further heat exchanger ( 27 . 28 ), in particular by means of a subsection ( 5 ) arranged switching valve ( 31 . 32 ) can be activated and deactivated. Cooling system according to claim 14, characterized in that the at least one further heat exchanger ( 27 . 28 ) is integrated in a transmission oil circuit or a clutch oil circuit. Cooling system according to one of claims 6 to 15, characterized in that a in the Bypass ( 18 ) integrated heat exchanger ( 24 ) leading bypass line ( 26 ) during the cold start or a warm-up phase of the internal combustion engine by means of the bypass switching device ( 22 ) is deactivated, so that a decoupling of the heat exchanger ( 24 ) is present.

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