Method and device for adjusting defined coolant flows in cooling systems of internal combustion engines in motor vehicles

Abstract

Method for operating a cooling and heating circuit for motor vehicles with an internal combustion engine (1) cooled by coolant, in which an engine coolant pump (7) builds up a pressure which is sufficient to ensure, in conjunction with an actuator (6), the coolant flow and the coolant temperature within the internal combustion engine (1) under a wide variety of operating conditions, and in that a sufficient flow through the individual branches of the cooling and heating circuit can be adjusted by means of the actuator (6) or further actuators (2, 40), characterized in that a) a cooling circuit with a cooling branch (6a) through the internal combustion engine (1), a vehicle radiator (8), the actuator (6), which opens the cooling circuit when required, and an engine coolant pump (7), b) the heating circuit with heating branch (4a) passes through the engine coolant pump (7), the internal combustion engine (1), a cabin heat exchanger (4) and an actuator (2, 40) acting on the coolant flow of the heating circuit, c) an air-side control of the cabin air outlet temperature (5) is provided, d) the coolant flow in the heating circuit is not solely based on the heating power requirement, e) with a first setting of the coolant flow in the heating circuit for situations requiring cabin heating, in which the heating circuit is opened and the coolant flows through it, f) with a second setting of the coolant flow in the heating circuit for situations without the need for cabin heating, in which the heating circuit is closed and the coolant does not flow through it g) and with a third setting of the coolant flow in the heating circuit for situations where there is no need for cabin heating at very high engine speed, in which the heating circuit is opened and the coolant flows through it.

Description

[0001] The invention relates to a method for operating a cooling and heating circuit for motor vehicles with an internal combustion engine 1 cooled by coolant, in which an engine coolant pump 7 builds up a pressure which is sufficient to ensure, in conjunction with an actuator 6, the coolant flow and the coolant temperature within the internal combustion engine under a wide variety of operating conditions, and in which a sufficient flow through the individual branches of the cooling and heating circuit can be adjusted by means of the actuator 6 or further actuators.

[0002] In motor vehicles with coolant-cooled internal combustion engines, it is customary to define the coolant flow rates through the internal combustion engine and the individual branches of the cooling and heating circuit by having a coolant pump 7, driven by the mechanical power of the internal combustion engine 1, provide the delivery pressure and distribute it to the individual branches by means of a thermostat 6 or other actuators. The dimensioning of the system ensures that sufficient pressure potential is available to the engine coolant pump 7 under all operating conditions and in particular at all engine speeds. This is important for the safe operation of the internal combustion engine without the risk of overheating. However, there are components in the individual branches of the cooling and heating circuit that require a minimum coolant flow rate.A well-known example here is the cabin heat exchanger, for which, according to the vehicle air conditioning specifications, minimum coolant flow rates are generally defined, which must be ensured by those responsible for engine or vehicle cooling during the development process. Other examples include minimum coolant flow rates through the charge air cooler, cooling for the power electronics, etc.

[0003] In this context, the interactions between the pump characteristics of the engine coolant pump and the resistance characteristics of the internal combustion engine 1 and the individual branches of the cooling and heating circuit mean that the branch with the greatest pressure loss at the respective required flow rate significantly determines the requirements for the engine coolant pump and the flow rates in the other branches. Viewed very simply, adaptation to an increased pressure requirement can be achieved either by changing the pump size or pump speed or by appropriate throttling in the branches with a relatively low pressure requirement. A more elegant approach, and one that brings corresponding efficiency benefits, is to reduce the pressure requirement by subjecting the critical branch to design changes to reduce the pressure loss.

[0004] In this context, modern calculation methods now allow for highly precise tuning of the individual branches of the cooling circuit and also of the overall system. Nevertheless, tuning is highly dependent on the engine speed and also on the specific applications of the internal combustion engine 1 in different vehicles. This results in particularly complex optimization tasks when, in addition to the actual function, the package and synergy effects when using identical parts across entire vehicle platforms must be considered. In series production practice, this means that in many cases, increased pressure losses occur, particularly in cooler branch 6a and bypass branch 6b, as well as significantly excessive pump drive power.

[0005] But even if optimization is only performed for one vehicle type, the significantly different dimensions of the vehicle radiator and cabin heat exchanger, as well as the relatively strict requirements for the minimum coolant flow through the cabin heat exchanger at low engine speeds, generally result in a system design that results in increased power consumption of the engine coolant pump. Due to the characteristics of the commonly used centrifugal pumps, this leads to a somewhat excessive coolant flow rate and a decrease in the efficiency of the engine coolant pump, especially at rated speed.

[0006] These hydraulic losses are associated with fuel consumption disadvantages, but even the rated power is affected, especially at high engine speeds.

[0007] Against this background, modern cooling systems attempt, among other things, to reduce some of these losses by influencing the pump speed depending on the engine speed.

[0008] In the simplest case, this can be achieved using a viscous coupling in the pump drive, which creates a certain slip between the pump and engine speeds at high pump speeds. However, the effort and risk involved in large-scale production are not small, and the disadvantage of an oversized pump, e.g. to provide the idle flow, remains, and the mass and volume of the viscous coupling add further disadvantages. More complex solutions even involve separating the engine coolant pump from the internal combustion engine 1, or even using a purely electric drive for the engine coolant pump 7. Whether a purely electric pump drive can ultimately achieve a cost-effective improvement in overall efficiency depends to a large extent on the efficiency of the electrical components, in particular the alternator, and is currently still an open question.

[0009] In addition to these questions regarding the efficiency of the engine coolant pump across the entire characteristic map range of the heating and cooling system, there are applications where it is advantageous to set a precisely defined coolant mass flow. One example is heating control by throttling the coolant flow through the cabin heat exchanger. The usual approach here is to provide a sufficiently high pressure potential by means of the engine coolant pump 7 in conjunction with throttling, e.g., via the clock frequency of a solenoid valve, which is adjusted depending on the coolant temperature, heating requirement, and engine speed. In addition to the additional pressure loss at the open valve, the provision of the pressure potential, regardless of the set volume flow, requires a corresponding drive power and thus oversizing of the engine coolant pump power.The adjustment of a defined coolant flow by means of the described timing or even with a pure throttle control is relatively imprecise and slow and only suitable for relatively high coolant volume flows, which makes it problematic for future variants of cabin heating, in which even very small volume flows have to be adjusted to changed values ​​relatively precisely and often very quickly.

[0010] To summarize, when using engine-driven coolant pumps, the pump drive power and pump mass are oversized at many operating points to meet extreme requirements in individual cooling or heating branches. High coolant volume flows with high pressure differences in the branches without extreme requirements lead to performance and fuel consumption disadvantages, especially at high engine speeds.

[0011] To solve this problem, a number of proposals are known in the state of the art.

[0012] For example, DE 37 38 412 A1 discloses a cooling system with a first pump, which is driven by an internal combustion engine and is designed for a basic delivery rate, and a second electric coolant pump controlled by an electric switching device, which is in series with the first pump and is only switched on when required.

[0013] EP 1 074 705 A2 shows a cooling system in which an engine coolant pump driven directly by the internal combustion engine is dispensed with and instead two electrically driven engine coolant pumps are used.

[0014] DE198 31 901 A1 shows a cooling system for cooling an internal combustion engine with demand-based coolant flow rates, with a first pump which is assigned to a vehicle radiator circuit, and a second pump which can be controlled as an active element and which is assigned to a bypass circuit bypassing the vehicle radiator.

[0015] DE 195 47 402 A1 shows a heating circuit with an additional heater in which an undesirably high pressure loss in the additional heater at high coolant flow is avoided by a valve opening a bypass line to bypass the additional heater.

[0016] DE 38 31 959 A1 discloses an electric auxiliary pump for a heating circuit with an integrated valve that opens due to the volume flow of the electric auxiliary pump.

[0017] DE 199 08 088 A1 shows a cooling system of an internal combustion engine with an electric auxiliary pump for a heating circuit, which is connected to a point with a comparatively high coolant mass flow, extracts a coolant volume flow there and feeds this downstream to the same branch with a high coolant volume flow.

[0018] Depending on their design, the improvement approaches described in the cited prior art lead to very considerable additional costs and development risks for newly developed special components such as special pumps and valves and / or for replacing the mechanically driven engine coolant pump with one or more electrically driven engine coolant pumps.

[0019] In contrast, the object of the present invention is to design a cooling and heating circuit for motor vehicles of the type described above which can be implemented simply and cost-effectively, in which on the one hand the minimum criteria for the coolant flow rate in all branches of the cooling and heating circuit are still ensured, but on the other hand also part of the potential for minimizing the pump drive power is used, which is lost in the prior art because excessive pump power is used to meet minimum coolant flow rates of individual branches at certain operating points or for special vehicle installations.

[0020] This object is achieved by the methods and devices according to the independent patent claims.

[0021] The dependent claims relate to preferred embodiments of the invention.

[0022] In particular, in preferred embodiments of the invention, a design of the cooling and heating circuit including a method for controlling or regulating the flow rates can be realized, which allows not only to ensure the minimum flow rates but also to set the most precisely defined values ​​possible. Depending on the sub-requirements or the hardware used, the potential control range can extend from the lowest to the highest engine speeds and down to very low flow rates. Fig. 1 shows a particularly advantageous embodiment of an engine and vehicle cooling system for implementing the method according to the invention. The coolant is pumped through the internal combustion engine 1 by the engine coolant pump 7. From the internal combustion engine outlet, the coolant flows in a first circuit 9a to the water tank 9 and then via the thermostat 6 back to the internal combustion engine 1. A second branch of the cooling system runs via line 6a and the vehicle radiator 8 to the thermostat 6 or directly to the thermostat 6 via the bypass branch 6b. Starting at a certain operating temperature, the thermostat 6 opens the radiator branch 6a more and more and closes the bypass branch 6b in a similar manner.

[0023] In addition to branches 6a, 6b, and 9a for vehicle cooling and venting the cooling system, branch 4a serves to heat the vehicle cabin. The coolant is pumped from the auxiliary pump 2 via the additional temperature sensor 15 to the cabin heat exchanger 4 and then back to the thermostat 6.

[0024] The coolant flow rate through the cabin heating branch 4a is deliberately set to low values ​​of, for example, only 2 l / min, using the engine control unit 16. The pipe cross-sections have an internal diameter of only 4-6 mm instead of the usual 16-20 mm. The cabin heat exchanger is also designed for a relatively high pressure drop in order to achieve high coolant flow velocities and good heat transfer in the individual heat transfer tubes. In contrast to the standard cross-flow heat exchanger, the counterflow design is preferably used here, which usually has a higher pressure drop on the water side anyway.

[0025] By installing an electric auxiliary pump 2, which, in contrast to the centrifugal pumps commonly used in vehicle cooling, is particularly advantageously designed as a diaphragm, piston, or gear pump, in conjunction with the inventive design of the cabin heat exchanger and the coolant lines for a very low coolant volume flow and high pressure losses, a coolant throughput in the heating circuit is achieved that is largely independent of the engine speed. This is due not least to the fact that the cooling system of today's internal combustion engines typically aims for the most moderate pressure and power requirements of the engine-side engine coolant pump 7. When using, for example, a gear pump as auxiliary pump 2, the flow through the cabin heat exchanger is therefore primarily determined by the electrical power of the gear pump and not by the engine coolant pump 7.Due to the low volume flow, the electrical power consumption of the auxiliary pump 2 is almost negligible for the on-board voltage network, even at high delivery pressure.

[0026] For further energy optimization, not only is the pressure loss in the heating circuit 4a deliberately set to a multiple of the pressure loss in the radiator branch 6a or bypass branch 6b, but the base engine and its cooling circuit are also modified at the same time. In this context, it has been common practice in the design of cooling systems in passenger cars to dimension the system so that the engine coolant pump 7 delivers a relatively high cooling water mass flow through the individual branches of the cooling circuit, and in particular through the cabin heat exchanger, even at idle. Due to the characteristics of the commonly used centrifugal pumps, this then leads to a somewhat excessive coolant volume flow and a drop in the efficiency of the engine coolant pump 7 at rated speed.Another design measure in current series production practice is the deliberate provision of a certain minimum pressure loss in the cooler and bypass branches 6a and 6b to ensure a sufficiently high coolant flow rate in the heater branch at low engine speeds. Both design measures lead to increased power consumption of the engine coolant pump 7, particularly at high engine speeds, due to increased pressure loss in the components or the slightly excessive coolant flow rate, which results in a decrease in the efficiency of the engine coolant pump.

[0027] On the one hand, this is associated with disadvantages in fuel consumption. Especially at high engine speeds, however, even the rated power of the internal combustion engine is affected. An estimation of the flow and discharge pressure at rated power, taking into account the pump efficiency, shows that 0.5 to 1 kW of engine power can be unnecessarily lost. Since the method according to the invention Fig. 1 the electric auxiliary pump controls the flow through the cabin heat exchanger, this conflict of objectives is defused.

[0028] The constant volume flow can be adjusted even more precisely with a piston pump or any other type of dosing pump than with a gear pump 2.

[0029] However, with an appropriate design of the auxiliary electric pump 2 and particularly high pressure losses in the heating circuit, a precisely defined flow rate can also be set with a conventional electric centrifugal pump, independent of the engine speed. It is already advantageous to set the pressure loss in the heating branch at least twice as high as in the radiator or bypass branch. However, significantly higher pressure loss differences are not only permissible but even desirable.

[0030] It is a particularly advantageous feature of the inventive design according to Fig. 1, the total pressure loss when opening the cooler branch 6a does not need to be kept constant by simultaneously closing the bypass branch, e.g., to prevent fluctuations in heating output. The necessary throttling in the bypass branch 6b to compensate for the pressure loss in the cooler 8 can thus be eliminated. To minimize the pressure loss, it is advantageous, among other things, if the water-side pressure loss in the cooler branch 6a is significantly greater than in the bypass branch 6b.

[0031] With appropriate optimization of all components involved, in particular by adjusting the pressure losses in the thermostat, the pressure loss in the heating branch 4a can easily be increased by a whole order of magnitude or more above the pressure loss in the cooling branch 6a. This can significantly improve the accuracy and consistency of the volume flow in the heating circuit. The option of using conventional small electric centrifugal pumps and still achieving very fine and rapid dosing by means of the deliberately very high pressure loss difference is of great economic interest, not least because pumps already in series production in very large quantities can be used. This not only minimizes costs, but also facilitates rapid series introduction and minimises the risk of large-scale production. Even this variant with electric...Centrifugal pump 2 and heating branch 4a designed for a very high pressure loss is still very effective in terms of energy. This is due, among other things, to the fact that the engine coolant pump 7 can not only be made smaller and lighter, but also operates at a significantly lower power across the entire operating map, and these effects more than compensate for the energy expenditure for the electric centrifugal pump 2. This is already the case in applications with relatively high coolant volume flows in the heating branch 4a. Not least, this is due to the synergy between the pressure loss savings in the cooler branch 6a and bypass branch 6b on the one hand, and the required pressure loss difference between these branches and the heating branch 4a on the other: the lower the pressure loss in branches 6a and 6b, the less pressure potential needs to be dissipated in the heating branch 4a in order to achieve the most defined flow possible through the heating branch 4a, regardless of the speed of the internal combustion engine.The embodiment of the method according to the invention presented here, which can achieve the full cabin heating output even with a coolant throughput of 2 l / min water / glycol mixture, also has the advantage of a particularly small electrical auxiliary pump 2 and, due to the low volume flow, only a very low electrical power consumption, even at pressure losses that are considered extremely high for cabin heating systems.

[0032] In the inventive mode of operation of the heating system, such a high control accuracy of the coolant flow rate can be achieved that, for example, a highly precise control of the cabin heating output can be carried out by means of an additional electrical pump 2. However, if the full potential of the cooling system according to Fig. 1 for the cabin heating and for the heat management of the internal combustion engine 1 to save fuel, the flow in the heating branch will not be based solely on the heat output requirement, but in particular on the highly variable cooling and heating situation that arises, for example, in city traffic due to the strong variation in the waste heat available from the internal combustion engine. In order to control the heat flows in the entire cooling and heating system, it is necessary, for example, to make rapid changes in the coolant flow so that the engine waste heat can be focused either on the cabin or on the internal combustion engine 1 itself. This optimization of the flow in the heating branch can be carried out in such a way that no temperature fluctuations occur in the cabin, but the full fuel saving potential may not be utilized.The air-side control intervention opens up additional degrees of freedom for varying the defined coolant flow in heating branch 4a.

[0033] Particularly in internal combustion engines, where the bypass branch 6b can be closed by the engine control system as needed, even when the cooler branch 6a is closed, in order to increase heating performance or reduce fuel consumption, the requirements regarding the accuracy and adjustability of the defined coolant volume flow through the heating branch 4a are very high. Especially in the example shown here according to Fig. 1, with very low coolant volume flow and very small pipe cross-sections, a very fast adaptation to changing flow specifications is also required, because due to the low heat-active mass, fluctuations in the engine outlet temperature very quickly become effective in the cabin heat exchanger. The fast and precise adjustment of the coolant volume flow made possible by the method according to the invention is very advantageous here in order to realize the full potential for reducing the heat-active masses in the heating circuit. When integrating an additional heat source 3, as in Fig. As shown in Figure 2, the precise adjustment of defined coolant flows through heating branch 4a takes on even greater significance. This concerns, among other things, the sensitivity to changes in engine speed and, most notably, the compensation of potential performance fluctuations of the auxiliary heat source 3, such as those unavoidable when using an exhaust gas heat exchanger.

[0034] Depending on the required precision for the coolant flow rate, the maximum value of the required coolant flow rate and the scope for the pressure loss, but also depending on the cost situation, it may be advantageous to work with less pressure loss and to realize the defined coolant volume flow in the branch with the electric auxiliary pump using a separate control system.

[0035] In its simplest version, the defined coolant flow rate, e.g., for cabin heating after a cold start, is set using an electric miniature gear pump with a specified voltage. As the cooling water gradually warms up, the viscosity will decrease. When using conventional DC motors with a fixed voltage, the pump speed and thus the flow rate will increase slightly due to a reduction in pressure loss.

[0036] This is not a problem for this application, but can easily be compensated for by the engine control using the cooling water temperature.

[0037] The special requirements of each individual branch, and in particular the accuracy of the dosing and the control range will ultimately decide which pump type and what additional effort is used for those branches that require a defined coolant flow independent of the speed of the internal combustion engine. In terms of energy, it is often optimal to equip all critical branches, particularly if they manage with a relatively low coolant volume flow, with an additional electric pump 2, so that no consideration needs to be given to the requirements of the branches with an additional pump 2, in particular the heating circuit 4a. However, it is often more cost-effective to only equip particularly poor branches with an additional electric pump 2 and to be content with the losses at a reduced level. In this case, it is advantageous to reduce the pressure loss in the branches that do not have an electric pump.Auxiliary pump 2, so that the minimum coolant flow rate is achieved in the branch with the highest pressure requirement. In the example in . Fig. 1, due to the possibility of optimising the thermostat and the bypass, this already brings a drastic improvement with corresponding potential to reduce the pump drive power.

[0038] Depending on the application and the pump design, the discharge pressures of the electric coolant pump 2 can be so high that it is advantageous to consider the temperature dependence of the coolant viscosity when adjusting the coolant flow rate. To minimize peak pressures, it is advantageous, especially in systems with a sharp pressure increase at low coolant temperatures, to locate the auxiliary pump 2 downstream of the cabin heat exchanger.

[0039] In situations where cabin heating is not required, it is advantageous in many applications to switch off the auxiliary electric pump 2, thus protecting the pump and eliminating the need for electrical power. It is particularly advantageous for rapid engine warm-up if the flow through the heating branch 4a is completely prevented. Depending on the pump design, the pump itself will ensure this. However, if, for example, a conventional electric centrifugal pump is used, a not insignificant leakage mass flow will occur despite the high pressure loss of the method according to the invention. This is undesirable for reasons of fuel consumption and emissions. Furthermore, it often has a disruptive effect on the vehicle air conditioning system.

[0040] Therefore, a particularly advantageous embodiment of the method according to the invention proposes Fig. 2, the branch with the electric auxiliary pump 2 has a valve 40 for preventing flow through the electric auxiliary pump 2, which valve opens when the electric auxiliary pump 2 is switched on. It is advantageous if the valve cannot be opened by the engine coolant pump 7 alone, at least up to a defined engine speed. Opening at very high engine speeds may be necessary in this context, for example, to prevent cavitation of the engine coolant pump 7.

[0041] The integration of the branch with the additional pump 2 takes place in Fig. 1 and Fig. 2 in the form of a separate circuit 4a. However, this is not absolutely necessary, especially if the coolant flow taken is relatively small.

[0042] The example in Fig. 3 shows a device in which the branch with the electric auxiliary pump 2 is connected to the coolant outlet of the internal combustion engine, i.e. to a branch with a comparatively high coolant flow. With a conventional thermostat 6, a relatively high coolant volume flow will always be present at this point. If a relatively low coolant volume flow is withdrawn at this point and fed back downstream to the same branch with a high coolant volume flow, the cooler branch 6a or the bypass branch 6b and thus the engine cooling remain unaffected. Equally important, however, is the fact that the relatively large total flow of these two branches prevents the coolant cooled in the heating heat exchanger from flowing back into the electric auxiliary pump without special additional measures. This means that the method according to the invention according to Fig.1 can be integrated into existing branches at almost any point with relatively low coolant withdrawal. Furthermore, this advantageous property can even be used in such a way that the branch with the electric auxiliary pump 2 is integrated at any point into a first branch with little sensitivity to changes in the coolant flow, extracts the required coolant volume flow there, and feeds it back downstream to any branch with little sensitivity to changes in the coolant flow.

[0043] A particularly advantageous feature of the method according to the invention is that the flexible integration into the engine cooling system allows for very short coolant lines for the cabin heater. This not only simplifies the package but also reduces costs, especially the weight and heat-active mass of the heating circuit.

[0044] The previous explanations have been made under the assumption that the auxiliary pump 2 has an electric drive. This is also the most advantageous drive method given the low power requirement and the degrees of freedom for adjusting various flow values. Nevertheless, many advantages of the method according to the invention are still retained if a different drive type, in particular a hydraulic or mechanical drive, is used instead of the electric drive of the auxiliary pump.

Claims

[1] Method for operating a cooling and heating circuit for motor vehicles with an internal combustion engine (1) cooled by coolant, in which an engine coolant pump (7) builds up a pressure which is sufficient to ensure, in conjunction with an actuator (6), the coolant flow and the coolant temperature within the internal combustion engine (1) under a wide variety of operating conditions and in which a sufficient flow through the individual branches of the cooling and heating circuit can be adjusted by means of the actuator (6) or further actuators (2, 40), characterized by , that a) a cooling circuit with a cooling branch (6a) through the internal combustion engine (1), a vehicle radiator (8), the actuator (6), which opens the cooling circuit when required, and an engine coolant pump (7), b) the heating circuit with heating branch (4a) passes through the engine coolant pump (7), the internal combustion engine (1), a cabin heat exchanger (4) and an actuator (2, 40) acting on the coolant flow of the heating circuit, c) an air-side control of the cabin air outlet temperature (5) is provided, d) the coolant flow in the heating circuit is not solely based on the heating power requirement, e) with a first setting of the coolant flow in the heating circuit for situations requiring cabin heating, in which the heating circuit is opened and the coolant flows through it, f) with a second setting of the coolant flow in the heating circuit for situations without the need for cabin heating, in which the heating circuit is closed and the coolant does not flow through it g) and with a third setting of the coolant flow in the heating circuit for situations without need for cabin heating at very high engine speed, in which the heating circuit is opened and the coolant flows through it. [2] Method according to claim 1, characterized by that the third setting is made to avoid cavitation of the engine coolant pump (7) at very high engine speed. [3] Method according to one of claims 1-2, characterized by that it is used in an internal combustion engine (1) through which fuel can flow via a cooler circuit with a cooler branch (6a) with the vehicle cooler (8) and via a bypass circuit with a bypass branch (6b) which bypasses the vehicle cooler (8), wherein the bypass branch (6b) can be closed as required by the engine control (16) even when the cooler branch (6a) is closed by the actuator (6) in order to reduce fuel consumption. [4] Method according to one of claims 1-3, characterized by that it is used in an internal combustion engine (1) through which heat can flow via a cooler circuit with a cooler branch (6a) with the vehicle cooler (8) and via a bypass circuit with a bypass branch (6b) which bypasses the vehicle cooler (8), wherein the bypass branch (6b) can be closed as required by the engine control (16) even when the cooler branch (6a) is closed by the actuator (6) in order to increase the heating output. [5] Method according to one of claims 1-4, characterized by that the pressure loss in the actuator (6) is minimized by installing an additional electric pump (2) in the heating circuit. [6] Method according to claim 5, characterized by that a valve (40) is used in the heating circuit which can only be opened by switching on the electric auxiliary pump (2), at least up to a defined engine speed. [7] Method according to one of claims 1-6, characterized bythat a separate control is used as a means of adjusting the coolant flow in the heating circuit. [8] Method according to one of claims 1-7, characterized by that the coolant flow in the heating circuit is not only based on the heating power requirement for the cabin heating, but also on the current cooling situation of the internal combustion engine (1). [9] Device for operating a cooling and heating circuit for motor vehicles with an internal combustion engine (1) cooled by coolant, in which an engine coolant pump (7) builds up a pressure which is sufficient to ensure, in conjunction with a first actuator (6), the coolant flow and the coolant temperature within the internal combustion engine (1) under a wide variety of operating conditions and in which a sufficient flow through the individual branches of the cooling and heating circuit can be adjusted by means of the first actuator (6) or further actuators (2, 40), with a) a cooling circuit with a cooling branch (6a) containing the internal combustion engine (1), a vehicle radiator (8), the actuator (6) which opens the cooling circuit when required, and an engine coolant pump (7), b) an engine ventilation circuit parallel to the radiator circuit, which leads from the internal combustion engine (1) via a coolant tank (9) and the engine coolant pump (7) back to the internal combustion engine (1), c) a bypass circuit parallel to the radiator circuit with a bypass branch (6b) which leads from the internal combustion engine (1) via the engine coolant pump (7) back to the internal combustion engine (1), d) a heating circuit parallel to the radiator circuit with a heating branch (4a) which leads from the internal combustion engine (1) via a cabin heat exchanger (4) and the engine coolant pump (7) as well as an actuator (2, 40) acting on the coolant flow of the heating circuit back to the internal combustion engine (1), e) an air-side control of the cabin air outlet temperature (5), wherein f) in situations where cabin heating is not required, the heating circuit is temporarily closed by a valve (40) acting on the coolant flow of the heating circuit, which valve cannot be opened by the engine coolant pump (7) alone, at least up to a defined engine speed, g) the actuator (2, 40) acting on the coolant flow of the heating circuit is open in situations where there is no need for cabin heating at very high engine speeds, h) the actuator (2, 40) acting on the coolant flow of the heating circuit is open in situations where cabin heating is required. [10] Device according to claim 9, characterized by that the actuator (2, 40) is open to avoid cavitation of the engine coolant pump (7). [11] Device according to one of claims 9-10, characterized bythat it is used in an internal combustion engine (1) in which the bypass branch (6b) can be closed as required by the engine control (16) even when the cooler branch (6a) is closed in order to reduce fuel consumption. [12] Device according to one of claims 9-11, characterized by that it is used in an internal combustion engine (1) in which the bypass branch (6b) can be closed as required by the engine control (16) even when the cooler branch (6a) is closed in order to increase the heating output. [13] Device according to one of claims 9-12, characterized by that a valve (40) is installed in the heating circuit as an actuator acting on the coolant flow of the heating circuit. [14] Device according to one of claims 9-13, characterized bythat a valve (40) is used as the actuator in the heating circuit acting on the coolant flow of the heating circuit, which valve can only be opened by switching on an additional electric pump (2), at least up to a defined engine speed. [15] Device according to one of claims 9-13, characterized by that a separate control is used as an actuator acting on the coolant flow of the heating circuit to adjust the flow in the heating circuit. [16] Device according to claim 13, characterized by that an additional electric pump (2) is installed in the heating circuit in the form of a centrifugal pump, which completely prevents the coolant volume flow in the heating circuit by switching off the electric drive by means of the motor control (16) and the valve (40) in the heating circuit. [17] Device according to one of claims 9-13, characterized bythat the pressure loss in the actuator (6) is minimized by installing an additional electric pump (2) in the heating circuit. [18] Device for operating a cooling and heating circuit for motor vehicles with an internal combustion engine (1) cooled by coolant, in which an engine coolant pump (7) builds up a pressure which is sufficient to ensure, in conjunction with an actuator (6), the coolant flow and the coolant temperature within the internal combustion engine (1) under a wide variety of operating conditions and in which a sufficient flow through the individual branches of the cooling and heating circuit can be adjusted by means of the actuator (6) or further actuators (2), characterized by , that a) a cooling circuit with a cooling branch (6a) through the internal combustion engine (1), a vehicle radiator (8), the actuator (6), which opens the cooling circuit when required, and an engine coolant pump (7), b) the heating circuit with heating branch (4a) passes through the engine coolant pump (7), the internal combustion engine (1), a cabin heat exchanger (4) and an actuator (2) acting on the coolant flow of the heating circuit, c) an air-side control of the cabin air outlet temperature (5) is provided, d) the coolant flow in the heating circuit is not solely based on the heating power requirement, whereby e) an engine control (16) of the internal combustion engine (1) adapts the coolant flow of the heating circuit to the current cooling and heating situation via the actuator (2) acting on the coolant flow of the heating circuit, (f) it is provided that the heating circuit can change from the closed to the open state in situations where there is no need for cabin heating, and g) the air-side control intervention (5) opens up these additional degrees of freedom for varying the coolant flow in the heating circuit. [19] Method for operating a cooling and heating circuit for motor vehicles with an internal combustion engine (1) cooled by coolant, in which an engine coolant pump (7) builds up a pressure which is sufficient to ensure, in conjunction with an actuator (6), the coolant flow and the coolant temperature within the internal combustion engine (1) under a wide variety of operating conditions and in that a sufficient flow through the individual branches of the cooling and heating circuit can be adjusted by means of the actuator (6) or further actuators (2, 40), with a) a cooling circuit with a cooling branch (6a) containing the internal combustion engine (1), a vehicle radiator (8), the actuator (6) which opens the cooling circuit when required, and an engine coolant pump (7), b) an engine ventilation circuit parallel to the radiator circuit, which leads from the internal combustion engine (1) via a coolant tank (9) and the engine coolant pump (7) back to the internal combustion engine (1), c) a bypass circuit parallel to the radiator circuit with a bypass branch (6b) which leads from the internal combustion engine (1) via the engine coolant pump (7) back to the internal combustion engine (1), d) a heating circuit parallel to the radiator circuit with a heating branch (4a) which leads from the internal combustion engine (1) via a cabin heat exchanger (4), an electric auxiliary pump (2) and the engine coolant pump (7) as well as a valve (40) acting on the coolant flow of the heating circuit back to the internal combustion engine (1), e) an air-side control of the cabin air outlet temperature (5), wherein f) in situations where there is no need for cabin heating, the heating circuit is temporarily closed by an actuator (40) acting on the coolant flow of the heating circuit, which actuator cannot be opened by the engine coolant pump (7) alone, at least up to a defined engine speed, g) the actuator (40) acting on the coolant flow of the heating circuit is opened in situations where cabin heating is required, h) the bypass branch (6b) is closed by the engine control (16) as required, even when the cooler branch (6a) is closed, in order to increase the heating output in situations where cabin heating is required, and i) the bypass branch (6b) is closed as required by the engine control unit (16) even when the cooler branch (6a) is closed in order to reduce fuel consumption. [20] Method according to claim 19, characterized bythat the actuator (40) acting on the coolant flow of the heating circuit is temporarily opened in situations where there is no need for cabin heating. [21] Method according to claim 20, characterized by that the actuator (40) acting on the coolant flow of the heating circuit is temporarily opened in order to avoid cavitation of the engine coolant pump (7).

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