Coolant circuit for cooling an internal combustion engine, in particular for a motor vehicle, and methods for operating such a coolant circuit

Abstract

A coolant circuit (10) for cooling an internal combustion engine (12) for a motor vehicle, comprising a cylinder housing (14) through which coolant flows and a cylinder head (16) of the internal combustion engine (12) through which coolant flows and which is connected to the cylinder housing (14), which are to be cooled by means of the respective coolant, wherein the coolant circuit (10) comprises a first coolant sub-circuit (18) in which the cylinder head (16) and at least one first radiator (22) are arranged, and a second coolant sub-circuit (20) in which the cylinder housing (14) and at least one second radiator (24) are arranged, and wherein the coolant sub-circuits (18, 20) are independently accessible to coolant flow, characterized in that a pump common to the coolant sub-circuits (18, 20) is provided for pumping the coolant through the coolant sub-circuits (18, 20).wherein the pump has a first flood through which the coolant of the first coolant sub-circuit (18) flows and a second flood through which the coolant of the second coolant sub-circuit (20) flows and which is separate from the first flood.

Description

[0001] The invention relates to a coolant circuit for cooling an internal combustion engine, in particular for a motor vehicle, according to the preamble of claim 1, and to a method for operating such a coolant circuit according to the preamble of claim 8.

[0002] Such a coolant circuit and a method for operating such a coolant circuit are known, for example, from EP 1 900 919 B1. The coolant circuit serves to cool an internal combustion engine, in particular for a motor vehicle. The internal combustion engine is designed as a reciprocating piston engine and has a cylinder housing and at least one cylinder head connected to the cylinder housing. The cylinder housing is also commonly referred to as the "engine block" or "cylinder block" because the cylinder housing has at least one combustion chamber in the form of a cylinder of the internal combustion engine.

[0003] The cylinder head and cylinder block are located within the coolant circuit and are each permeated by coolant. The cylinder block and cylinder head are cooled by heat transfer from the cylinder block and cylinder head, respectively, to the coolant flowing through them. The coolant is, for example, a cooling fluid, commonly referred to as "coolant water."

[0004] In the EP 1 900 919 B1, the coolant circuit can be operated in two different operating states. In the first of these states, the coolant flows only through the cylinder head, while it does not flow through the cylinder block. In other words, the cylinder block is not cooled in this first operating state. In this first operating state, the coolant flows to a heater core, which heats the air supplied to the vehicle's interior.

[0005] In the second operating state, coolant flows through both the cylinder head and the cylinder block. The cylinder block and cylinder head are connected in series. The coolant first flows through the cylinder head and then through the cylinder block.

[0006] DE 10 2010 060 319 A1 discloses an internal combustion engine comprising a coolant circuit. A main coolant pump, an auxiliary coolant pump, and a control element are arranged in the coolant circuit. The cooling circuit is designed as a cabin heat exchanger circuit, and the control element is designed as a check valve. The main coolant pump is arranged in the cabin heat exchanger circuit, with a connecting line branching off from the cabin heat exchanger circuit and opening into a cylinder block coolant jacket. The auxiliary coolant pump is arranged in the connecting line.

[0007] Furthermore, an internal combustion engine with a cylinder crankcase and a cylinder head is known from DE 102 19 481 A1. A cooling water circuit is also provided, comprising a first cooling water channel extending in the cylinder head between an inlet opening and an outlet opening, and a second cooling water channel extending separately in the cylinder crankcase between an inlet opening and an outlet opening, as well as a common cooling water pump arranged in the cooling water circuit. A third cooling water channel connects the outlet opening of the first cooling water channel in the cylinder head to the inlet opening of the cooling water pump. A fourth cooling water channel connects the outlet opening of the cooling water pump to the inlet opening of the second cooling water channel in the cylinder crankcase for conveying the cooling water from the first to the second cooling water channel.

[0008] DE 10 2011 004 998 A1 discloses a control device for a machine cooling system. DE 10 2008 049 204 A1 discloses a cooling system for liquid-cooled internal combustion engines. Furthermore, DE 10 2012 019 046 A1 discloses an internal combustion engine for a motor vehicle. Additionally, DE 101 39 314 A1 discloses a cooling system for motor vehicle engines.

[0009] The object of the present invention is to create a coolant circuit and a method of the type mentioned above, by means of which a particularly demand-oriented and thus improved cooling of the internal combustion engine can be achieved.

[0010] This problem is solved by a coolant circuit with the features of claim 1 and by a method with the features of claim 8. Advantageous embodiments with expedient and non-trivial further developments of the invention are specified in the remaining claims.

[0011] To further develop a coolant circuit of the type specified in the preamble of claim 1 in such a way as to achieve particularly demand-oriented and thus improved cooling of the internal combustion engine, the invention provides that the coolant circuit comprises a first coolant sub-circuit and a second coolant sub-circuit. The cylinder head and at least one first radiator are arranged in the first coolant sub-circuit. The cylinder housing and at least one second radiator are arranged in the second coolant sub-circuit. The second radiator is provided in addition to the first radiator. The coolant circuits can be independently traversed by coolant. In other words, the coolant sub-circuits can be traversed separately by the respective coolant.

[0012] Thus, it is possible, for example, that the first coolant circuit is filled with coolant while the second coolant circuit is not. In other words, the second coolant circuit remains completely empty. Furthermore, it is possible that the second coolant circuit is filled with coolant while the first coolant circuit remains empty.

[0013] Furthermore, it is possible for both coolant circuits to be simultaneously supplied with coolant, but the coolant circuits are connected in parallel, i.e., in parallel and not in series (i.e., one after the other). The coolant circuits are thus completely separated from each other, at least with regard to their respective flow rates, so that the cylinder block and cylinder head can be cooled according to specific requirements.

[0014] This makes it possible, for example, to specifically adapt the individual coolant circuits to the cooling requirements of the internal combustion engine. In other words, the coolant circuit can be specifically adapted to the cooling requirements of the cylinder head, while the second coolant circuit can be specifically adapted to the cooling requirements of the cylinder block. Since the coolant circuits are separate from each other, these adaptations can be carried out largely independently, and any mutual influence of the adaptations or cooling requirements can be avoided or at least minimized.

[0015] In particular, it is possible to adjust the coolant circuits to different coolant temperatures. The coolant in each circuit is preferably a liquid coolant that flows through the respective circuit. For example, the first coolant circuit can be set, and in particular regulated, to a coolant temperature of at least 70 degrees Celsius, while the second coolant circuit can be set, and in particular regulated, to a coolant temperature of at least 115 degrees Celsius. This allows the cooling of the cylinder head and its components to be optimized without excessively affecting the frictional performance in the cylinder housing (e.g., the crankcase) through overcooling.In other words, excessive cooling of the cylinder housing can be avoided due to the separate coolant circuits, allowing the cylinder housing to be brought up to an advantageous operating temperature particularly quickly and maintained at that temperature. This, in turn, keeps frictional power within the cylinder housing exceptionally low.

[0016] The cylinder housing is designed, for example, as a crankcase or cylinder crankcase, in which a number of components, such as the crankshaft and pistons of the internal combustion engine, are mounted on the cylinder housing so as to be movable relative to it. Because the temperature of the coolant in the second coolant circuit can be set at least essentially independently of the temperature of the coolant in the first coolant circuit, excessive cooling of the cylinder housing can be avoided.

[0017] Furthermore, in a corresponding operating state of the coolant circuit, a so-called "stationary" coolant can be implemented in the second coolant sub-circuit, meaning that the second coolant sub-circuit, and thus the cylinder housing, is not circulated by coolant. Due to the separation of the coolant sub-circuits, this stationary coolant, which reduces friction, can be maintained for a significantly longer period for the cylinder housing, for example during the warm-up phase of the internal combustion engine, than would be the case with a series arrangement of the coolant sub-circuits.

[0018] Furthermore, the coolant circuit according to the invention enables intelligent switching of individual components during operation, so that the coolant circuit as a whole can always be adapted to respective, changing operating conditions.

[0019] The coolant circuit according to the invention enables a particularly pronounced downsizing of the internal combustion engine. Such downsizing means that the internal combustion engine has a very small displacement and a relatively small number of cylinders, but simultaneously high specific power and high specific torque. This can be achieved, for example, by using at least one exhaust gas turbocharger. Typically, such downsizing of an internal combustion engine leads to a high energy input in the form of heat input into components of the internal combustion engine, especially the cylinder head. The coolant circuit according to the invention can accommodate this high energy input, since the cylinder head and the cylinder block can be cooled as needed and, in particular, at least substantially independently of each other.Due to the described interconnection of the coolant circuit with the coolant sub-circuits, the coolant flowing through the cylinder head can have a significantly lower temperature than the coolant flowing through the cylinder housing, so that on the one hand the cylinder head can be cooled particularly strongly, but on the other hand a sufficiently high temperature of the cylinder housing can be achieved so that the frictional power in the cylinder housing can be kept low.

[0020] According to the invention, a pump common to the coolant sub-circuits is provided for pumping the coolant through the coolant sub-circuits, wherein the pump has a first flow through which the coolant of the first coolant sub-circuit flows and a second flow through which the coolant of the second coolant sub-circuit flows and which is separate from the first flow. In other words, in this embodiment, instead of two spatially separate pumps, a single structural unit is provided by means of which the coolant is pumped through the respective coolant sub-circuits.

[0021] By using the two separate floods, it is possible, for example, to adjust, in particular control or regulate, the pump common to the coolant sub-circuits in such a way that different flow rates of the respective coolant are achievable for each coolant sub-circuit.

[0022] It has proven particularly advantageous to have a heater core integrated into the first coolant circuit, allowing the air supplied to the vehicle's interior to be heated. This heat transfer occurs through heat exchange between the coolant flowing through the heater core and the air flowing through it. This placement of the heater core within the first coolant circuit allows the air to be heated particularly quickly, thus enabling rapid heating of the interior. This creates a so-called comfort heating system.

[0023] In a further advantageous embodiment of the invention, at least one exhaust gas turbocharger of the internal combustion engine is arranged in the first coolant circuit. The exhaust gas turbocharger can supply at least one combustion chamber, in the form of a cylinder of the cylinder housing, with compressed air, thus enabling particularly high specific power and high specific torque of the internal combustion engine. The arrangement of the exhaust gas turbocharger in the first coolant circuit allows for particularly effective cooling of the turbocharger.

[0024] Another embodiment is characterized by the fact that at least one lubricant heat exchanger for heating a lubricant, in particular an oil, of the internal combustion engine is arranged in the first coolant circuit. This lubricant heat exchanger can be a so-called oil heat exchanger, by means of which, for example, engine oil is cooled for lubricating and / or cooling the internal combustion engine. Furthermore, the lubricant heat exchanger can be a so-called transmission oil heat exchanger, by means of which transmission oil is cooled for lubricating and / or cooling and / or actuating a transmission of the internal combustion engine. It has proven particularly advantageous if at least one oil heat exchanger and one transmission oil heat exchanger are arranged in the first coolant circuit.

[0025] In a particularly advantageous embodiment of the invention, a valve element is arranged upstream of the lubricant heat exchanger, which can be switched between at least one release position and at least one closed position. In the release position, the lubricant heat exchanger, i.e., the oil heat exchanger and / or the transmission oil heat exchanger, is supplied with the coolant from the first coolant circuit. In the closed position, however, the lubricant heat exchanger is not supplied with the coolant from the first coolant circuit. This activation or activation of the lubricant heat exchanger allows vehicle components, such as the transmission and / or components of the internal combustion engine that are lubricated, to be cooled as needed and, in particular, to be heated as needed and very quickly, thereby bringing them to an advantageous operating temperature.

[0026] Another embodiment is characterized by the provision of a common expansion tank for both coolant circuits, through which both coolant circuits can be supplied with coolant, and in particular, filled. In other words, it can be provided that the two coolant circuits, which are completely separated from each other in terms of flow, can be filled and / or emptied via the same common port, so that essentially the same medium, in particular a coolant fluid, flows in both coolant circuits. This allows the number of parts and the installation space required for the coolant circuit to be kept particularly low.

[0027] Finally, it has proven particularly advantageous if at least one of the coolant circuits has a bypass path through which the respective coolant can bypass the radiator. Such a bypass means that the coolant flowing through the bypass path does not pass through the radiator. In other words, the coolant flowing through the bypass path avoids the radiator and therefore is not cooled by it. This allows for particularly rapid and demand-based heating of the relevant components of the internal combustion engine.

[0028] The invention also includes a method of the type specified in the preamble of claim 10, wherein, to achieve particularly efficient and improved cooling of the internal combustion engine, the coolant circuit comprises a first coolant sub-circuit in which the cylinder head and at least one first radiator are arranged, and a second coolant sub-circuit in which the cylinder housing and at least one second radiator are arranged. In the first operating state, the coolant is passed through the first coolant sub-circuit and thus through the cylinder head and the first radiator, while it does not flow through the second coolant sub-circuit. In other words, in the first operating state, the second coolant sub-circuit, and thus the cylinder housing and the second radiator, are not subjected to coolant flow.

[0029] In the second operating state, the respective coolant is passed through the second coolant sub-circuit and, in parallel, through the first coolant sub-circuit. Advantageous embodiments of the coolant circuit according to the invention are to be regarded as advantageous embodiments of the method according to the invention, and vice versa.

[0030] The method includes a pump common to the coolant sub-circuits, by means of which the coolant is conveyed through the coolant sub-circuits, wherein the pump has a first flood through which the coolant of the first coolant sub-circuit flows and a second flood through which the coolant of the second coolant sub-circuit flows and which is separate from the first flood.

[0031] Further advantages, features, and details of the invention will become apparent from the following description of a preferred embodiment and from the drawing. The features and combinations of features mentioned above in the description, as well as those mentioned below in the figure description and / or shown in the figures alone, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention.

[0032] The drawing shows in: Fig. 1 a schematic representation of a coolant circuit for cooling an internal combustion engine, wherein the coolant circuit has two fluidically separated coolant sub-circuits, which can be independently supplied with coolant for cooling the internal combustion engine; Fig. 2 a schematic representation of the coolant circuit, which is operated in a first operating state; Fig. 3 another schematic representation of the coolant circuit, which is operated in a second operating state; Fig. 4 another schematic representation of the cooling medium circuit, which is operated in a third operating state; Fig. 5 another schematic representation of the coolant circuit, which is operated in a fourth operating state; Fig. 6 another schematic representation of the coolant circuit, which is operated in a fifth operating state; Fig. 7 another schematic representation of the coolant circuit, which is operated in a sixth operating state; Fig. 8 a further schematic representation of the coolant circuit, which is operated in a seventh operating state; and Fig. 9 another schematic representation of the coolant circuit, which is operated in an eighth operating state.

[0033] In the figures, identical or functionally equivalent elements are provided with the same reference numerals.

[0034] Fig. Figure 1 shows a schematic representation of a coolant circuit, designated as 10, for cooling an internal combustion engine 12 of a motor vehicle, for example, a passenger car. The internal combustion engine 12 is a reciprocating piston engine and comprises a cylinder housing 14, which is designed as a cylinder crankcase. The cylinder housing 14 has a plurality of combustion chambers in the form of cylinders. Furthermore, an output shaft in the form of a crankshaft of the internal combustion engine 12 is rotatably mounted on the cylinder housing 14 about an axis of rotation relative to the cylinder housing 14. Each cylinder contains a piston, which is translationally movable relative to the respective cylinder. The pistons are articulated to the crankshaft via connecting rods, so that the translational movements of the pistons are converted into a rotational movement of the crankshaft about its axis of rotation.Inside the cylinder housing 14 is a cooling jacket, also referred to as a "water jacket," which at least partially surrounds the respective cylinders. A coolant in the form of a cooling fluid flows through the cooling jacket, so that the cylinder housing 14, and in particular the cylinders, can be cooled by heat transfer from the cylinder housing 14 to the coolant flowing through it.

[0035] The internal combustion engine 12 further comprises a cylinder head 16, which is connected to the cylinder housing 14. At least one camshaft, for example, is rotatably mounted on the cylinder head 16 about an axis of rotation relative to the cylinder head 16. The cylinder head 16 also has at least one cooling jacket through which a coolant, in particular a cooling liquid, can flow. As a result of heat transfer from the cylinder head 16 to the coolant flowing through the cylinder head 16, the cylinder head 16 can be cooled.

[0036] To achieve particularly efficient cooling of the cylinder housing 14 and the cylinder head 16, the coolant circuit 10 comprises a first coolant sub-circuit 18 and a second coolant sub-circuit 20. The cylinder head 16 is located in the first coolant sub-circuit 18. Furthermore, a first radiator in the form of a main water radiator 22 is located in the first coolant sub-circuit 18. This means that the cylinder head 16 and the main water radiator 22 are exposed to the coolant flowing through the first coolant sub-circuit 18.

[0037] The cylinder housing 14 is located in the second coolant circuit 20. Furthermore, a second radiator in the form of a wheel arch radiator 24 is located in the second coolant circuit 20. Thus, the cylinder housing 14 and the wheel arch radiator 24 are exposed to the coolant flowing through the second coolant circuit 20.

[0038] As a result of the aforementioned heat transfer from the cylinder head 16 to the coolant of the first coolant circuit 18, the coolant of the first coolant circuit 18 is heated. The heated coolant of the first coolant circuit 18 can then be cooled by heat transfer from the coolant flowing through the main water cooler 22, via the main water cooler 22, to the air flowing around the main water cooler. The main water cooler 22 thus acts as a heat exchanger.

[0039] As a result of the described heat transfer from the cylinder housing 14 to the coolant of the second coolant circuit 20, the coolant of the second coolant circuit 20 is heated. The coolant flowing through the second coolant circuit 20 can be cooled by heat transfer from the coolant of the second coolant circuit 20 flowing through the wheel arch radiator 24, via the wheel arch radiator 24, to the air flowing around the wheel arch radiator 24. Thus, the wheel arch radiator 24 also acts as a heat exchanger.

[0040] In Fig. 1 A fan wheel 26 of a fan can also be seen, by means of which the wheel arch cooler 24 can be supplied with an airflow flowing around the wheel arch cooler 24.

[0041] The coolant sub-circuits 18 and 20 are independently supplied with coolant. This means that the two coolant sub-circuits 18 and 20 are completely separated from each other in terms of flow. It is possible for the coolant sub-circuits 18 and 20 to be supplied from a common expansion tank and, if necessary, filled and emptied via this expansion tank. In this case, the two coolant sub-circuits 18 and 20 can be connected only by a single filling line or at least via the same expansion tank. Thus, despite the flow separation of the coolant sub-circuits 18 and 20, the coolant circuit 10 requires only one expansion tank.

[0042] The expansion tank and the two filling lines to the two coolant sub-circuits 18, 20 are not shown in the figures and, according to the known state of the art, can be connected to the two coolant sub-circuits 18, 20 at any suitable position, whereby, as already mentioned, either two separate lines lead from the expansion tank to the two coolant sub-circuits 18, 20 or one filling line that opens into both coolant sub-circuits 18, 20, but has no influence on the flow characteristics of the two coolant sub-circuits 18, 20.

[0043] In Fig. Figure 1 shows a sensor control unit 30, which is connected via sensor lines to various positions on the two coolant sub-circuits 18 and 20. It uses sensors to measure various parameters, such as temperature, pressure, and other readings of the cooling system, and processes and provides these for controlling the coolant circuit 10, also for other control units of a vehicle with such a coolant circuit 10. Among many other measured values, the temperatures at the cylinder head 16, the cylinder block 14, and the main water radiator 22 are particularly important for the coolant circuit 10, so that in Fig. Figure 1 and all other figures show the sensor control unit 30 with sensor lines to the cylinder head 16, to the cylinder housing 14 and to the main water cooler 22 as an example, whereby for the sake of clarity, a representation of further sensor lines and control lines, in particular to controllable valves, has been omitted without excluding them from the invention.

[0044] The complete separation of the coolant circuits 18 and 20 allows for a large temperature difference between them, ensuring optimal cooling of the cylinder head 16 while preventing unnecessary heat loss from the cylinder housing 14. For example, this makes it possible to set or regulate the coolant flowing through coolant circuit 18 to a temperature of at least 70 degrees Celsius, while the coolant in coolant circuit 20 can be set or regulated to a higher temperature, such as 115 degrees Celsius.In the case of cooling operation, the cylinder housing 14, which functions as a crankcase, therefore releases less heat to the coolant of the coolant circuit 20 due to the higher temperature level in the coolant circuit 20 compared to the coolant circuit 18, and the wheel arch radiator 24 is sufficient to dissipate the amount of heat introduced into the coolant flowing through the coolant circuit 20.

[0045] A first thermostat 32 is arranged in the coolant sub-circuit 18, by means of which the distribution or flow of the coolant in the first coolant sub-circuit 18 is controlled. The thermostat 32 sets the coolant in the first coolant sub-circuit 18 to a temperature of 70 degrees Celsius.

[0046] A second thermostat 34 is arranged in the second coolant circuit 20, by means of which the distribution or flow of the coolant in the second coolant circuit 20 is set or controlled. The second thermostat 34 sets or regulates the coolant temperature of the second coolant circuit 20 to 115 degrees Celsius.

[0047] In the first coolant circuit 18, a pump 36 is arranged for pumping the coolant of the first coolant circuit 18. In addition, another pump 38 is arranged in the first coolant circuit 18, which can be an auxiliary pump.

[0048] In the second coolant circuit 20, a pump 40 is arranged for circulating the coolant of the second coolant circuit 20. The pump 36 is arranged in the flow direction of the coolant of the first coolant circuit 18 between the main water radiator 22 and the cylinder head 16. Accordingly, with respect to the flow direction of the coolant of the second coolant circuit 20, the pump 40 is arranged between the wheel arch radiator 24 and the cylinder housing 14. The radiator (wheel arch radiator 24) of the second coolant circuit 20 is referred to as a wheel arch radiator because it is located in the area of ​​a right-hand wheel arch of the passenger car (relative to the direction of forward travel) and is supplied with air via this wheel arch to cool the coolant of the second coolant circuit 20. The pumps 36 and 40 are designed as separate components. Alternatively, the pumps 36 and 40 can be combined into a single component unit.

[0049] Out of Fig. Figure 1 shows that a heating heat exchanger 42 is arranged in the first coolant circuit 18. The heating heat exchanger 42 is also referred to as a "heating water heat exchanger" and is permeable to the coolant of the first coolant circuit 18 and to air. As a result of heat transfer from the coolant of the first coolant circuit 18 via the heating heat exchanger 42 to the air flowing through the heating heat exchanger 42, the air can be heated. The air is then supplied, for example, to the interior of a passenger vehicle to heat the interior.

[0050] In the first coolant circuit 18, an exhaust gas turbocharger 44 is also arranged. The exhaust gas turbocharger 44 comprises, for example, at least one turbine which can be driven by exhaust gas from the internal combustion engine 12. Furthermore, the exhaust gas turbocharger 44 includes a compressor driven by the turbine, by means of which air is compressed. The air compressed by the compressor can be supplied to the cylinders of the internal combustion engine 12, thus enabling particularly efficient and fuel-efficient operation of the internal combustion engine 12.

[0051] The exhaust gas turbocharger 44 is permeable to the coolant of the first coolant circuit 18 and can therefore be cooled as a result of heat transfer from the exhaust gas turbocharger 44 to the coolant of the first coolant circuit 18 flowing through the exhaust gas turbocharger 44.

[0052] Out of Fig. Figure 1 shows that the heater core 42 and the exhaust gas turbocharger 44 are arranged in a bypass path 46 of the first coolant circuit 18. The coolant of the first coolant circuit 18 can bypass the main water cooler 22 via the bypass path 46. In other words, the coolant flowing through the bypass path 46 does not pass through the main water cooler 22 and is therefore not cooled by the main water cooler 22. Instead, the coolant of the first coolant circuit 18 can flow past the heater core 42 and the exhaust gas turbocharger 44, bypassing the main water cooler 22 and returning to the pump 36 via the pump 38.

[0053] The bypass path 46 is also referred to as a "bypass" or "short circuit". The second coolant sub-circuit 20 also has a bypass path 48. The coolant from the second coolant sub-circuit 20 bypasses the wheel arch cooler 24 via the bypass path 48. This means that the coolant flowing through the bypass path 48 does not flow through the wheel arch cooler 24 and is therefore not cooled by it. Instead, the coolant from the coolant sub-circuit 20 can flow back to the pump 40 after the thermostat 34, bypassing the wheel arch cooler 24.

[0054] Out of Fig. Figure 1 further shows that a first lubricant heat exchanger in the form of a transmission oil heat exchanger 50 is arranged in the first coolant circuit 18. The transmission oil heat exchanger 50 is also referred to as a "transmission oil-water heat exchanger" and is permeable to transmission oil. The passenger car, for example, has a transmission coupled or connectable to the internal combustion engine 12, which is to be lubricated and / or cooled and / or actuated by means of the transmission oil. The transmission oil can flow through the transmission oil heat exchanger 50. Furthermore, the coolant of the first coolant circuit 18 can flow through the transmission oil heat exchanger 50. As a result of heat transfer from the transmission oil via the transmission oil heat exchanger 50 to the coolant of the first coolant circuit 18, the transmission oil is cooled.

[0055] Furthermore, an additional lubricant heat exchanger in the form of a so-called oil heat exchanger 52 is arranged in the first coolant circuit 18. The oil heat exchanger 52 is also referred to as an "oil-water heat exchanger" and is permeable to engine oil for lubricating and / or cooling the internal combustion engine 12. The engine oil heat exchanger 52 is also permeable to the coolant of the first coolant circuit 18. This allows the engine oil to be cooled by heat transfer from the engine oil via the engine oil heat exchanger 52 to the coolant of the first coolant circuit 18. As a result of the respective heat transfer from the transmission oil or the engine oil to the coolant of the coolant circuit 18, the coolant of the coolant circuit 18 is heated.

[0056] Upstream of the lubricant heat exchangers (transmission oil heat exchanger 50 and engine oil heat exchanger 52), a valve 54 is arranged in the coolant sub-circuit 18. As will be described in more detail below, the valve 54 is adjustable or switchable between at least one enabling position and at least one closed position. In the enabling position, the lubricant heat exchangers are supplied with the coolant of the first coolant sub-circuit 18. In the closed position, however, the lubricant heat exchangers are not supplied with the coolant of the first coolant sub-circuit 18. Fig. 1 it can be seen that the valve 54 has three ports 56a-c, wherein at least part of the ports 56a-c can be selectively closed or opened.

[0057] In the first coolant circuit 18, a third pump 58 is arranged for circulating the coolant of the first coolant circuit 18. Furthermore, another radiator in the form of a transmission subcooler 60 is also arranged in the first coolant circuit 18. The transmission subcooler 60 is also designed as a heat exchanger and is permeable to the coolant of the first coolant circuit 18. Air also flows around the transmission subcooler 60. As a result of heat transfer from the coolant of the first coolant circuit 18 flowing through the transmission subcooler 60 to the air flowing around the transmission subcooler 60, the coolant of the first coolant circuit 18 can be cooled by means of the transmission subcooler 60.

[0058] Furthermore, in Fig. Figure 1 shows a low-temperature cooler 62, which is also designed as a heat exchanger, for example. The low-temperature cooler 62 can also be a component of the coolant circuit 10. The low-temperature cooler 62 is, for example, arranged in a low-temperature cooling circuit, which is not shown in these exemplary embodiments and is only indicated by the illustrated low-temperature cooler 62, and through which a coolant, in particular a cooling liquid, can flow. Compared to the coolant of the coolant sub-circuit 18 and the coolant sub-circuit 20, however, the coolant flowing through the low-temperature cooling circuit has a lower temperature level.

[0059] Furthermore, in Fig. 1 A cooler in the form of a wheel arch cooler 64 is visible, which is arranged in the low-temperature cooling circuit. The coolant flowing through the low-temperature cooling circuit (not shown in the figures) can be cooled by means of the low-temperature cooler 62 and the wheel arch cooler 64. In Fig. 1 Directional arrows illustrate possible flow directions of the respective coolant. A throttle valve 66 is arranged in the coolant sub-circuit 18.

[0060] The thermostat 32 has connections 68 and 69, whereby the coolant of the coolant sub-circuit 18 can flow into the thermostat 32 via connection 68. For example, by opening or closing connections 68 and / or 69 as needed, it can be set whether or not the thermostat 32 is supplied with coolant from the coolant sub-circuit 18.

[0061] Within the framework of a method for operating the coolant circuit 10, this circuit can be operated in different operating states. Based on Fig. Figure 2 illustrates one of these operating states. In the first operating state, for example, port 56a of valve 54 is closed, and ports 56b and 56c may also be closed. Furthermore, the coolant in the first coolant circuit 18 has a temperature below 70 degrees Celsius. Therefore, ports 68 and / or 69 of thermostat 32 are also blocked, so that thermostat 32 does not allow coolant to flow to the main water cooler 22.

[0062] The thermostat 34 has three connections 70, 72, and 74. Connection 70, 72, and / or 74 can be selectively opened or closed. Coolant that has flowed into the thermostat 34 via the open connection 70 can flow out of the thermostat 34 via connections 72 and 74 when the respective connection 72 or 74 is open.

[0063] In the first operating state, the coolant of the second coolant circuit 20 has a temperature of less than 50 degrees Celsius. Therefore, for example, the connections 72 and 74 of the thermostat 34 are closed, so that the coolant cannot flow through the thermostat 34.

[0064] Out of Fig. Figure 2 shows that the coolant of coolant sub-circuit 18 flows through the cylinder head 16, but not through the thermostat 32. Instead, it is diverted beforehand and flows through the heater core 42 and the exhaust gas turbocharger 44. Following this, the coolant of coolant sub-circuit 18 flows back to the cylinder head 16 via pumps 38 and 36. The coolant of coolant sub-circuit 18 thus flows into a so-called smallest circuit of the cylinder head 16.

[0065] In the first operating state, there is no coolant flow through the cylinder housing 14. In other words, the cylinder housing 14 is not cooled by the coolant from the coolant partial circuit 20 in the first operating state. This means that in the first operating state, the coolant is stagnant within the cylinder housing 14. This so-called stagnant coolant does not cool the cylinder housing 14, or only very slightly, so that, for example, during the warm-up phase of the internal combustion engine 12, it can be heated up particularly quickly and brought to a sufficient operating temperature. At this operating temperature, favorable lubrication conditions exist, since, for example, the engine oil has a suitably high temperature.

[0066] This allows the internal friction and thus the fuel consumption of the internal combustion engine 12 to be kept low, especially during the warm-up phase. In the initial operating state, the cylinder head 16, the heater core 42, and the exhaust gas turbocharger 44 form the smallest possible circuit via the bypass path 46. For example, immediately after the internal combustion engine 12 is started, the heater core 42 is supplied with the coolant from the first coolant circuit 18, which is heated by the cylinder head 16. In the initial operating state, the coolant is also heated by the exhaust gas turbocharger 44. This allows the passenger car's interior to be supplied with warm air very soon after the internal combustion engine 12 is started, thus enabling a so-called comfort heating system.

[0067] By regulating and controlling the pumping capacity of pump 38, the amount of coolant flowing through the bypass path 46 can be adjusted, so that any remaining coolant pumped by pump 36 flows directly from the cylinder head 16 to pump 36 via a throttle 66. This allows coolant to flow in a small circuit even when no heating power is being drawn from the heater core 42 and the exhaust gas turbocharger 44 requires little or no cooling.

[0068] Based on Fig. Figure 3 illustrates a second operating state. The second operating state differs from the first in that the coolant present in the cylinder housing 14 is no longer the same; instead, the coolant from the second coolant circuit 20 circulates through the cylinder housing 14, the thermostat 34, and back to the cylinder housing 14 via the pump 40. In this state, port 72 of the thermostat 34 is closed, while port 74 and port 72 of the thermostat 34 are open. Coolant that has flowed into the thermostat 34 via the open port 70 can flow out of the thermostat 34 via the respective ports 72 and 74 when these ports are open.

[0069] Since, in the second operating state, port 72 is blocked and port 74 is open, the coolant flowing into thermostat 34 via port 70 can exit thermostat 34 via port 74. This means the coolant does not flow to and through wheel arch cooler 24, but instead flows from thermostat 34 into bypass path 48 and through it. Thus, the coolant flowing through bypass path 48 can bypass wheel arch cooler 24 and flow directly from thermostat 34 back to cylinder housing 14 via pump 40. For example, in the second operating state, cylinder housing 14 is cooled more effectively compared to the first operating state. However, in both the second and first operating states, the coolant in the second coolant circuit 20 is not cooled by wheel arch cooler 24.In the second operating state, as in the first operating state, the connection 69 of the thermostat 32 is blocked, so that the thermostat 32 is not supplied with coolant from the first coolant sub-circuit 18.

[0070] Furthermore, the port 72 of the thermostat 34 is fluidically blocked, so that the coolant from the second coolant circuit 20 flowing into the thermostat 34 cannot flow to the wheel arch cooler 24. The port 74 is open, so that the coolant flowing into the thermostat 34 can leave the thermostat via port 74 and flow into the bypass path 48.

[0071] Based on Fig. Figure 4 illustrates a third operating state. In the third operating state, as in the first, a coolant is present in the cylinder housing 14. However, unlike the first operating state, ports 56b and 56a are open, while port 56c may be closed. As a result, in the third operating state, the lubricant heat exchangers are activated, unlike in the first and second operating states, and are supplied with coolant from the first coolant circuit 18. However, in the third operating state, the transmission oil and engine oil are not cooled. Instead, the transmission oil is heated via the transmission oil heat exchanger 50, and the engine oil via the engine oil heat exchanger 52. This is because, in the third operating state, the coolant from the first coolant circuit 18 is still at a higher temperature than the engine and transmission oil.By heating the engine oil and the transmission oil in this way, the transmission and the internal combustion engine 12 can be heated up particularly quickly and brought to a sufficient operating temperature.

[0072] Based on Fig. Figure 5 illustrates a fourth operating state of the coolant circuit 10. This fourth operating state corresponds to the third operating state, except that the coolant of the second coolant sub-circuit 20 is not located in the cylinder housing 14, but flows through the bypass path 48. In the fourth operating state, the transmission oil and the engine oil are also heated via the lubricant heat exchangers (oil heat exchanger 52 and transmission oil heat exchanger 50).

[0073] In Fig. Figure 6 illustrates a fifth operating state. The fifth operating state differs from the fourth in that the coolant of the first coolant circuit 18 now has a temperature of 70 degrees. This causes the thermostat 32 to open its connection 69, allowing the coolant of the first coolant circuit 18 to flow through the thermostat 32 and from there to the main water cooler 22. This coolant of the first coolant circuit 18 is thus cooled by the main water cooler 22, resulting in a first-stage cooling process in the fifth operating state. Therefore, the temperature of the coolant of the first coolant circuit 18 can be kept essentially constant at 70 degrees Celsius.Depending on the temperature difference between the coolant of the first coolant circuit 18 and the transmission oil or the engine oil, the transmission oil and the engine oil are either cooled or further heated by the lubricant heat exchangers. This can also be applied to the following operating conditions.

[0074] Fig. Figure 7 shows a sixth operating state of the coolant circuit 10. In the sixth operating state, the cylinder head 16 is cooled on a second stage. Fig. Figure 7 shows that ports 56b, 56c, and 56a of valve 54 are open, allowing the coolant of the first coolant circuit 18 to flow from valve 54 to both the lubricant heat exchangers and the transmission subcooler 60. This allows the coolant of the first coolant circuit 18 to be cooled by both the transmission subcooler 60 and the main water cooler 22.

[0075] Fig. Figure 8 shows a seventh operating state of the coolant circuit 10. In the seventh operating state, the cylinder head 16 is cooled on a third stage. In the seventh operating state, the port 56a of the valve 54 is closed, while ports 56b and 56c are open. This means that, for example, port 56a can also be fluidically blocked (i.e., closed) or fluidically opened (i.e., opened) as needed.

[0076] The coolant of the first coolant circuit 18 flows from the thermostat 32 to the main water cooler 22, and from the main water cooler 22, for example, partly back to the pump 36 and partly to the transmission subcooler 60. From the transmission subcooler 60, the coolant of the first coolant circuit 18 flows to and into the valve 54, since the port 56c is open. The coolant of the first coolant circuit 18, which has flowed into the valve 54 via the open port 56c, can flow out of the valve 54 via the open port 56b and thus to and through the lubricant heat exchangers. From the lubricant heat exchangers, the lubricant can then flow back to the pump 36 and to the cylinder head 16 via the pump 58.

[0077] Fig.Figure 9 shows an eighth operating state of the coolant circuit 10. In the eighth operating state, the cooling effect of the coolant circuit 10 is set to its maximum. In the eighth operating state, the connection 74 of the thermostat 34 is fluidically blocked, i.e., closed, while the connection 72 is open.

[0078] This is the case because the coolant of the second coolant circuit 20, for example, has a temperature of 115 degrees Celsius. As a result, the thermostat 34 opens the path to the wheel arch cooler 24, allowing the coolant of the second coolant circuit 20 to flow through the thermostat 34 to the wheel arch cooler 24 and through the wheel arch cooler 24. This cools the coolant of the second coolant circuit 20 by means of the wheel arch cooler 24. Thus, the temperature of the coolant of the second coolant circuit 20 can be kept essentially constant at 115 degrees Celsius. Incidentally, the eighth operating state corresponds to the seventh operating state.

[0079] The complete fluid-dynamic separation of the coolant sub-circuits 18 and 20 allows for a significant expansion of the control and regulation options and a broader parameter range of the cooling system compared to conventional coolant circuits. This enables even finer control of the various operating conditions described, which is particularly advantageous for cooling high-performance engines. However, the coolant circuit 10 can also be used in all other engines, not just high-performance engines.

[0080] Valve 54 enables the lubricant heat exchangers to be activated as needed, thus allowing the smallest circuit mentioned above to be expanded depending on the temperature. This allows the transmission and engine oil to be additionally heated using the warm coolant from cylinder head 16. Valve 54 makes it possible to implement the four circuits already described: 1. Standing coolant 2 Heating 3 Cooling stage 1 with warmer coolant 4 Cooling stage 2 with strongly cooled coolant.

[0081] During the entire warm-up phase of the internal combustion engine 12, the coolant can remain stationary in the cylinder housing 14, allowing the oil film on the respective cylinder walls to heat up as quickly as possible. Because the coolant sub-circuit 20, designed as a crankcase circuit, is separate from the coolant sub-circuit 18, there is no need to consider temperature hotspots in the cylinder head 16 and therefore the stationary coolant does not need to be dispersed earlier. As soon as the respective temperatures reach operating level, the thermostats 32 and 34 regulate the coolant sub-circuits 18 and 20 to a preset temperature and control the respective flow rate through the respective radiators. Reference symbol list 10 Coolant circuit 12 Internal combustion engine 14 cylinder housings 16 cylinder head 18 first coolant sub-circuit 20 second coolant sub-circuit 22 Main water coolers 24 wheel arch coolers 26 fan wheel 30 Sensor control unit 32 Thermostat 34 Thermostat 36 Pump 38 Pump 40 pump 42 heating heat exchangers 44 exhaust gas turbochargers 46 Bypass path 48 Bypass path 50 transmission oil heat exchangers 52 oil heat exchangers 54 valve 56a-c connector 58 Pump 60 Gearbox subcoolers 62 Low-temperature coolers 64 Wheel arch coolers 66 Throttle valve 68 connection 69 connection 70 connection 72 connection 74 connection

Claims

[1] Coolant circuit (10) for cooling an internal combustion engine (12) for a motor vehicle, comprising a cylinder housing (14) through which coolant flows and a cylinder head (16) of the internal combustion engine (12) through which coolant flows and which is connected to the cylinder housing (14), which are to be cooled by means of the respective coolant, wherein the coolant circuit (10) comprises a first coolant sub-circuit (18) in which the cylinder head (16) and at least one first radiator (22) are arranged, and a second coolant sub-circuit (20) in which the cylinder housing (14) and at least one second radiator (24) are arranged, and wherein the coolant sub-circuits (18, 20) are independently through which coolant flows, characterized by, that a pump common to the coolant sub-circuits (18, 20) is provided for pumping the coolant through the coolant sub-circuits (18, 20), wherein the pump has a first flood through which the coolant of the first coolant sub-circuit (18) flows and a second flood through which the coolant of the second coolant sub-circuit (20) flows and which is separate from the first flood. [2] Coolant circuit (10) according to claim 1, characterized by , that in the first coolant circuit (18) a heating heat exchanger (42) is arranged, by means of which air which is to be supplied to an interior of the motor vehicle can be heated. [3] Coolant circuit (10) according to claim 1 or 2, characterized by , that at least one exhaust gas turbocharger (44) of the internal combustion engine (12) is arranged in the first coolant circuit (18). [4] Coolant circuit (10) according to any of the preceding claims, characterized by, that in the first coolant circuit (18) at least one lubricant heat exchanger (50, 52) is arranged for heating a lubricant. [5] Coolant circuit (10) according to claim 4, characterized by , that upstream of the lubricant heat exchanger (50, 52) a valve element (54) is arranged which is switchable between at least one enabling position, in which the lubricant heat exchanger (50, 52) is supplied with the coolant of the first coolant sub-circuit (18), and at least one closed position, in which the lubricant heat exchanger (50, 52) is not supplied with the coolant of the first coolant sub-circuit (18). [6] Coolant circuit (10) according to any of the preceding claims, characterized by , that a common expansion tank is provided for the coolant sub-circuits (18, 20), through which both coolant sub-circuits (18, 20) can be supplied with coolant. [7] Coolant circuit (10) according to any of the preceding claims, characterized by , that at least one of the coolant sub-circuits (18, 20) has at least one bypass path (46, 48) by which the respective cooler (22, 24) can be bypassed by the respective coolant. [8] Method for operating a coolant circuit (10) for cooling an internal combustion engine (12) for a motor vehicle, comprising a cylinder housing (14) through which coolant flows and a cylinder head (16) through which coolant flows and which is connected to the cylinder housing (14), which are to be cooled by means of the respective coolant, wherein the coolant circuit (10) is optionally operated in a first operating state or in at least a second operating state different from the first operating state, wherein the coolant circuit (10) comprises a first coolant sub-circuit (18) in which the cylinder head (16) and at least one first radiator (22) are arranged, and a second coolant sub-circuit (20) in which the cylinder housing (14) and at least one second radiator (24) are arranged, wherein in the first operating state the coolant is passed through the first coolant sub-circuit (18),while the flow through the second coolant sub-circuit (20) is omitted, and wherein in the second operating state the respective coolant is passed through the second coolant sub-circuit (20) and in parallel through the first coolant sub-circuit (18), , characterized by , that a pump common to the coolant sub-circuits (18, 20) is provided, by means of which the coolant is conveyed through the coolant sub-circuits (18, 20), wherein the pump has a first flood through which the coolant of the first coolant sub-circuit (18) flows and a second flood through which the coolant of the second coolant sub-circuit (20) flows and which is separate from the first flood.

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