DE102004058865A1 - Cooling and heating circuit operation method for motor vehicle, involves supplying cooling water at position upstream of motor coolant pump in cooling system, where pump is opened at each position of closed thermostatic valve - Google Patents

Abstract

The method involves including an exhaust branch that varies the flow of cooling agent in a bypass branch and is controlled by an electronic motor control (20). The exhaust circuit supplies its cooling water at a position upstream of a motor coolant pump in a cooling system. The motor coolant pump is opened at each position of a closed thermostatic valve (6) for the motor coolant pump. An independent claim is also included for a device for cooling and heating of a motor vehicle.

Description

The invention relates to a method and an apparatus for operating a cooling and heating circuit for motor vehicles with an internal combustion engine 1 by means of an engine coolant pump 7 circulated coolant is cooled, with a self-sufficient thermostatic valve 6 , which for controlling the coolant temperature, the coolant flow rate through the internal combustion engine 1 and the vehicle radiator branch 6a governs, with a bypass branch 6b which additionally varies the coolant flow rate through the internal combustion engine as a function of its cooling requirement, a heating branch 4a and a vent branch 9a , It is particularly suitable for the operation of internal combustion engines with a conventional expansion thermostat.

It is known in modern cars by means of thermal management measures to reduce fuel consumption. A quick heating of the coolant and the engine oil and thus also the engine components and the raising of the thermostat opening temperature in partial load are proven means to fuel economy improvements to realize.

Future strategies to achieve the full fuel saving potential by such measures include in particular ways, the opening time of the thermostat by means of the motor control and to choose freely the coolant flow rate to vary in wide ranges by the engine during warm-up. There are different ones for this solutions available, from the magnetic clutch to the shutdown of the coolant pump the engine over pump internal short circuit valves up to fully variable el. Water pump as a replacement for the Belt-driven cooling water pump.

all known solutions for controlling the coolant flow rate By the engine is common that considerable cost of the necessary additional components attack. In addition to the measures to regulate the flow through the engine is at most known optimization strategies in particular the replacement of the today's usual thermostats with control of the radiator flow by means of Expansion element by a freely controllable by the engine control Valve provided. For the full exploitation of the potential in this context in particular relatively expensive valves provided, in which the flow through the radiator from the engine control given and over a stepper motor sensitively is set. Set different rotational positions of the multi-way valve then e.g. preferred positions for optimal hot cooling, a maximum cooling effect or a maximum cabin heating power. The cost of such a Valve to multiple inflows and outflows et al For the radiator, the bypass and to switch the heating circuit or vary continuously, are not irrelevant. In addition, there is an additional expense, if a sufficient Fail-safe behavior for all potential summer and winter operating conditions should be realized.

The Costs are therefore already considerable, even if under waiver the full fuel saving potential is waived, at the same time as the introduction the valve also an additional measure for varying the coolant pump speed or the coolant pump delivery rate provided.

Not most recently against the background of costs and operational safety has hitherto a much simpler system for hot cooling on Market prevailed, in which an expansion thermostat with an el. heatable expansion element the optional operation in two different Coolant temperatures allows. In this case, a thermostat is used with expansion element, which for example, from 100 ° C inevitably starts to open, at el. energization of the heating element of this opening time is then by means of the el. heat supply to the expansion element on e.g. 80 ° C postponed. The fuel consumption benefits are not here fully exhausted, et al because the effectiveness of the system on driving situations with coolant temperatures above about 80 ° C is limited, the additional costs are also much lower. About that In addition, there is any discussion regarding the robustness of the system and their fail-safe characteristics as well as the question of availability Ready-to-fit components in view of the already existing series experience with this kind of el. heated thermostats largely without object.

Yet the system suppliers work for motor vehicle cooling systems to the variants described above for the full utilization of the Fuel saving potential of thermal management measures. The success of these new solutions However, on the one hand, it has a significant impact on the development of emissions legislation and fuel prices coupled, on the other hand, very strong to the provision of much cheaper hardware than before available. Conversely, just the lack of mass production startup hampers falling hardware prices for the el. multi-way valve as Thermostatisatz and possibly the switching or adjustable cooling water pump.

Even if now a well-known car manufacturer for a whole engine family, the high cost of a cooling system with electrically driven engine cooling water pump operates to save as much fuel, yet prevent the high cost in many places the introduction of such System.

Not last therefore are recent Time cheaper systems, such. the el. thermostat in three-plate design in the serial application arrives. In such systems closes one the three plates - the so-called closing plate the small coolant circuit in the early Warm-up phase and opens with increasing engine warming. By means of el. Energization of the expansion element at high thermal If necessary, the bypass branch is opened further at very high cooling demand and wide open Radiator circuit closed again. The el. Energizing helps, in particular, earlier problems the three-disc thermostat when switching quickly from part load to counteract full load, especially when the engine is cold. The limited Response speed with cold cooling water, however, allows the use of three-liter thermostat still not on every engine without additional design measures to.

Also Systems with freely controllable bypass valve, e.g. as stepless controlled rotary valve, are known that do not have this problem but with respect to the cost again unfavorable lie.

all known systems including the Three-cardiovascular thermostat is common that special intervention in the Heating circuit necessary are to prevent the circulating in the heating circuit coolant has a negative effect on fuel consumption. To get inside the engine as warm as possible small water-side heat transfer coefficients as well as the heat-active masses and heat losses to minimize the heating circuit, are in the previously known Thermal management systems provided separate devices that allow the coolant throughput to prevent the heating branch during warm-up or at least strong to throttle. Especially with air-side control of the cabin heater i.a. additional costs for Coolant valves or other components for suppressing / throttling the heating volume flow at.

As already stated above have all known thermal management systems also the Peculiarity that the technical implementation of the hot-cooling, i. higher coolant or component temperatures in the partial load and lower values at full load, caused considerable costs. This applies to all known species Electrically controlled thermostatic valves in internal combustion engines, including the recently in the series application came three-liter thermostats. specially in this fall in addition to the cost of the el. heating of the expansion element the price for the shutdown or throttling of the heating circuit.

there let the opening and closing speed or the switching speed at the three-dial thermostat well still wishes open.

One little noticed detail in heat management measures is often the flow of the expansion tank. in principle are solutions on the market, which optionally leave the expansion tank open or this with an additional Close the valve or the flow artificially curb.

Also Applications where the return of the expansion tank connected to the cold cooler side is and the closed thermostat 6 prevents a flow during warm-up, are known. This is - thermal seen - one as effective as inexpensive Solution, which, however, with not to be underestimated disadvantages and risks for the Engine coolant pump accompanied. The cavitation tendency of the pump increases, associated with increased risks in terms of Pump life and sometimes a drop in flow. thermal equivalent or even superior is the solution with the additional Valve in the venting branch, especially when this el. Is switched by the engine control. Again, however, there are significant costs.

In contrast, lies the object of the present invention therein, a particularly cost-effective and yet reliable cooling and heating system, while maximizing the fuel savings potential of thermal management measures already at coolant temperatures below today in cooling systems without el. Thermostats usual Thermostat opening temperature can be used and which are also used in particular can, a large part of the fuel savings potential realize, for the one coolant temperature above today in cooling systems without el. Thermostats usual Thermostat opening temperature needed becomes.

When in particular desired or to be beaten corner points for the temperatures and costs are currently the values of el. heated thermostats to look at how they are to be found today in the market, i. especially Setting the coolant temperature to values between 80-85 ° C at high Load and 100-115 ° C in the partial load.

Especially should the features regarding Fuel saving and fast switching from partial load to Full load as well as the total system cost of the first this year once exceeded in Grosserie applied three-plate thermostats become.

Furthermore there is an ancillary requirement that the requirements regarding the Cabin heating effect unrestricted Fulfills should be. Even better it in this context, if the heating effect can be improved could or if in the partial load a switch between a first mode with significantly improved fuel consumption and a second Operating mode with improved heating performance and slightly less improved Fuel consumption could be realized.

These Task is solved by the method according to claim 1.

In the simplest version, a single additional valve switches 6bv with closed thermostat 6 at the same time all other cooling circuits including the vent branch 9a if necessary, on and off. This reduces the fuel consumption in the partial load by means of increased component temperatures without risks under increased load or increased cooling demand. At the same time, the risk of cavitation in both operating states is minimized by the system pressure always being applied to the pump inlet.

For el. Control of the additional valve 6bv In addition, it is possible during the first few seconds of warming up and, if necessary, from time to time to provide for a targeted venting by briefly opening.

In Connection to a part of the accompanying claims even the additional task of switching between a first mode with significantly improved fuel consumption and a second Operating mode with improved heating performance and slightly less improved Fuel consumption solved.

there open the individual design variants allow the designer the opportunity to Design emphasis on the costs to lay either and in particular with already available Including serial components of the heating heat exchanger get along, so that the additional costs in spite of significant fuel economy restrict to the additional valve. Alternatively, he can also by new heating heat exchangers in Gegenstrombauauart and / or optionally the use of el. additional pumps in the heating circuit with something elevated Costs increase both the fuel consumption advantage as well at the same time improve the heating comfort.

A particularly simple and inexpensive embodiment of the method according to the invention with - compared to known standard cooling systems - restriction of additional costs to only a single additional valve 6bv is exemplary in 1 shown.

Here is the focus on improving fuel economy at minimal cost with the option of switching to normal operation, i.e. on full functionality the cabin heating and cooling.

With additional valve open 6bv is the coolant according to 1 from the engine coolant pump 7 by the internal combustion engine 1 conveyed, flows through the additional valve 6bv in the bypass branch 6b to the convection expanding thermostat 6 , During warm-up, the radiator-side plate of the expansion thermostat closes the radiator circuit while the by-pass plate is open. The vent line 9a of the expansion tank 9 is downstream of the additional valve 6bv connected. From the expansion tank, the coolant flows together with the water from the heating return to the thermostat. This line is usually open and closed thermostat 6 to the engine coolant pump 7 open. Also downstream of the additional valve 6bv is the cooling water for the heating circuit 4a taken. The heating heat exchanger 4 is traversed at this setting in a conventional manner. As long as the additional valve 6bv In the open state only a relatively small pressure loss generated to achieve the full heating power no further redesign of the components must be made. Therefore, a rotary valve is preferably used as an additional valve, which releases the full channel cross section of the bypass line in the open state. Since the rotary valve is only operated on /, this is very simple and inexpensive to produce, most simply with a vacuum actuator of the one of the engine control 20 controlled solenoid valve is supplied with negative pressure. During warm-up without cabin heating demand is at low to medium engine load, the additional valve 6bv through the engine control 20 closed. This is not just the bypass cycle 6b interrupted but also the heating circuit 4a , the ventilation circuit 9a , the cooler circuit 6a and the flow through the oil cooler PRO. With the exception of a local flow in the vicinity of the pump impeller and the natural convection is thus standing in the cooling circuit stagnant water. This decreases in a known manner, the water-side heat transfer coefficient in the engine and it increases the internal coolant and component temperature. The reduction of friction by a warmer cylinder liner, slightly lower engine power the engine coolant pump, warmer oil and gasoline engines thermal Entdrosselung the intake air then ultimately lead to the characteristic fuel economy of this heat management measure. As long as overheating of the engine is reliably prevented by means of suitable sensors or thermal models, the additional valve can remain closed. If cavitation on the coolant pump is to be expected due to excessive pump speed, the motor opens control 20 the additional valve 6bv , Likewise if the thermal load is too high or at full motor load. The high actuating speed of the additional valve 6bv compared to the potential alternative "EI. Thermostat "not only considerably expands the range until the thermostat is opened for the first time, but also in terms of consistently avoiding potential cavitation on the coolant pump during speed jumps, the high positioning speed is very helpful first opening the additional valve advantageous.

The simplest strategy is to wait as long as possible until the additional valve opens and incorporates the bypass branch together with the oil cooler, heating circuit and degas circuit and, if necessary, slightly opens the cooler circuit. It may be advantageous for better ventilation, the first few seconds of warm-up still open with additional valve 6bv to work and, if necessary, during the warm-up still from time to time to vent by the auxiliary valve opens for a short time. In many engines, the repeated venting during the warm-up phase but also eliminated.

In particular, however, the strategy may also be advantageous to initially keep the additional valve closed, then open the additional valve when a first temperature below the thermostat opening temperature is reached, so that a first temperature compensation occurs in the bypass and heating branch and at the oil cooler 40 a heat transfer from the water to the oil sets. If necessary, the flow in the vent line must be additionally throttled here. It is up to the user, the additional valve 6bv to close again as soon as the water and the oil are largely at the level of the thermostat opening temperature. As long as no heating is needed, this has the advantage that the coolant, oil and component temperatures can then be further increased because the thermostat 6 then closes again in view of the lack of flow with hot cooling water.

So long no flow in the bypass branch and thus also in the heating branch, there is no danger that part of the heated one Cooling water over one part Open the radiator thermostat escapes.

A sudden opening of the additional valve 6bv leads with increased cooling demand directly to an increase in the heat transfer coefficient in the water jacket of the engine and thus to a cooling effect. A thermal shock risk does not exist because the thermostat 6 with additional valve open 6bv ensures in a known manner a successive admixing of cold cooling water from the radiator branch.

Possibly a clocked opening of the Additional valve, allowing also a gradual switching on the heater or the radiator is feasible.

The procedure of the invention does not claim to be the thermodynamically best way. Rather, the ratio of costs to benefits can always be seen here. Especially if the fuel consumption without additional demands on the heating effect in the foreground, the procedure according to the invention is advantageous. If at the same time an improvement of the heat output would be required, then starting from 1 a method with connection of the heating heat exchanger 4 upstream of the additional valve 6bv , Close the additional valve 6bv to improve the heating power, throttling the coolant flow rate through the engine and the heater core and countercurrent design of the heater core 4 much more effective. Such embodiments of the method according to the invention will be described in more detail later.

First shows 2 but still another embodiment of the inventive method with the main focus on the costs. In this embodiment, the heating return is between the thermostat 6 and engine coolant pump inlet arranged. The inlet to the heating branch 4a takes place upstream of the additional valve 6bv , Without its own valve in the heating branch is the heater core 4 flows through permanently already in warm-up, ie the heat-active wet of the heating circuit must be heated with, associated with disadvantages in fuel consumption. In return, the heating is always functional. A closing of the additional valve 6bv causes - at least compared to standard cooling systems with bypass branch and without heat management components - yet already a fuel economy advantage, because in the warm-up phase of the bypass branch 6b does not have to be heated with, because the total coolant flow through the engine 1 is reduced and because the flow through the expansion tank 9 is prevented. It is also cheaper ia the oil cooler 40 at least in the early warm-up phase does not flow through with coolant.

Another special feature compared to known cooling systems is in 2 the heater coolant flow is not through the thermostat 6 guided. This has three very particularly advantageous effects: On the one hand, the pressure loss when flowing through the thermostat does not affect the venting branch to a pressure difference, which otherwise might lead to a backward flow through the expansion tank 9 can lead. On the other hand, the heat-active masses and the heat losses are reduced by heat conduction to the bypass and to the cooling erzweig. As a third and no less important advantage allows the introduction downstream of the Dehnstoffthermostaten 6 it, the engine control 20 the decision to transfer, from which coolant temperature or other engine operating condition this by opening the additional valve 6bv the bypass branch 6b and optionally the cooler branch 6a switches on and thus sets an increased cooling effect. In other words, the engine can be operated at least temporarily without problems at elevated coolant temperature, without that by a partial opening of the thermostat 6 due to a flow of hot cooling water from the heating return heat is lost to the environment. This applies to operation with and without heat removal at the heating heat exchanger 4 ,

In the inventive method according to 2 In particular, the option to choose the coolant flow through the heater is largely attractive. So it is possible in particular, with a very ordinary Dehnstoffthermostaten 6 to operate with an opening temperature of, for example, 85 ° C and circulate both without cabin heating and with cabin heating all conceivable coolant temperatures up to 110-115 ° C in the heating circuit without the expansion thermostat 6 opens and inadvertently releases heat through the radiator 8th to the environment. In the simplest case, the integration of a simple on / off additional valve is sufficient 6bv , as in eg 2 is shown. As long as the additional valve 6bv remains closed, the expansion element is not flowed around by warm coolant, the thermostat remains closed. The circulating in the heating circuit coolant can thus either switched off by means of a valve or throttled by means of suitable component dimensioning or the use of positive displacement pumps or flow unhindered. In other words, the circulating in the heating circuit coolant can be used in a wide map range of the coolant temperature and the engine internal heat transfer coefficient for homogenizing or increasing the engine component temperature or for heating purposes.

At the same time, the additional valve 6bv sure that in a sudden increase in cooling demand, especially at full load, by the opening of the bypass branch component overheating is reliably avoided. The temperature monitoring can be model-based, among others, by the motor control or by means of the temperature measuring point 20a respectively.

Starting from cold radiator branch 6a At first, a high flow of coolant flows when the additional valve is open 6bv through the bypass branch 6b , where directly with the opening of the bypass branch already an increase of the water-side heat transfer coefficient within the engine is accompanied.

For longer cooling requirements, the resulting heat input leads to the expansion element of the thermostat 6 for the partial opening of the thermostat, ie a completely conventional temperature control, possibly up to the complete opening of the cooler branch 6a and close the bypass branch 6b by means of the expansion thermostat 6 , If the load jump is only short, then the additional valve closes 6bv if necessary, again and the engine works again with reduced flow on increased coolant and the component temperature.

The activation of the additional valve 6bv By means of the engine control offers the particular advantage that regardless of the coolant temperature can be switched at any time to full coolant flow through the engine. Especially motors of very high specific power can be very well protected during a load jump. The known by el. Thermostats dead times when opening and closing omitted, so that, for example, can be driven longer with stagnant or particularly hot water. Optionally, an on / off control of the additional valve 6bv respectively.

When further advantage leaves With this configuration, the risk of cavitation on the Engine cooling water pump at a higher engine speeds more reliable than for example with the three-disc thermostat.

Also if the previously described simple variants of the cooling and heating circuit according to the invention do not open up the full fuel saving potential and in comparison to previous patent applications with switchable additional valve with adjustment of the coolant throughput as well as the heating heat exchanger in addition to lower fuel savings, a much lower Cabin heating effect results, so do especially the simplicity and the cost aspect of these designs very attractive.

The costs for An on / off valve are so small, especially because such Valves are already in mass production and therefore the investments to keep very low in development and production. Likewise is so that the default risk is very small. This can be Additionally reduce, if one relies on valve types, the normally open are. This is especially true for Solenoid valves or valves with vacuum actuator.

The already low cost of the additional valve can be reduced even further, if you waive the free activation of the additional valve 6bv via the engine control 20 Use the coolant itself to control a pressure cell det, which then controls the valve directly via a linkage. When a certain pressure is exceeded, the inflowing cooling water shifts the membrane of the pressure cell against a spring force including the ambient pressure or the internal pressure of the can, thus opening the additional valve 6bv , Such a configuration, in contrast to conventional temperature monitoring has the advantage that not a single local overtemperature is monitored, but at any point resulting steam leads to an increase in pressure and thus ultimately opens the valve. At the same time, the valve opens at a suitable installation position with high static pressure, regardless of the temperature, even at high pressure, which is caused by high engine and thus pump speed. In other words, especially in the range of rated power there is no possibility of error due to incorrect temperature information. In addition, the cavitation risk of the engine coolant pump at high speed is turned off.

In particular, the fact that the local engine overheating is monitored via a single coolant pressure line and with a single self-contained component on the other hand eliminates the risk of cavitation on the superimposed by the engine coolant pump pressure, is a particularly helpful aspect of the directly controlled by the overpressure additional valve 6bv , This ensures on the one hand that at high engine speed regardless of the engine load very quickly opening the additional valve and cavitation is avoided, on the other hand, the cooling in the part-typical engine map area primarily limited to a minimum and at the same time thermally secured.

In addition, such a valve inevitably takes into account the fact that when approaching the rated power and the rated torque - these are in motor-typical engines ia at relatively high engine speeds on - immediately with open auxiliary valve 6bv is driven and that the additional valve even at partial opening of the radiator 8th remains open.

In the particularly preferred and in view of the high specific performance of future engines medium to long term also largely unavoidable variant of the method according to the invention, with conventional in the thermostat 6 Integrated two-valve valve for opposing closing and opening of radiator branch 6a and bypass branch 6b as well as with additional valve 6bv in the bypass branch, for example, the additional valve 6bv according to 10 even with closed bypass valve of the thermostat 6 ie when most of the coolant is above the radiator branch 6a flows, do not close again because the removal position of the control pressure 103 is at a point of high static pressure, for example, on the water jacket of the cylinder block or eg in accordance with 12 always by a relatively high pressure applied cooler line 6a upstream of the vehicle radiator and the auxiliary valve 6bv , The control line 20b is in 12 dashed lines, although this is also a coolant line to symbolize that this is only a control line in the pressure box 100 of the additional valve 6bv ends.

As with the activation of the additional valve 6bv via the engine control 20 the procedure according to the invention also has the particular advantage that by the extensive separation of the functions of the thermostat 6 from the tasks of the additional valve 6bv already a rough on / off control is sufficient. This separation of functions is not only important to the cost of the valve 6bv and to reduce their control, but it only makes it possible to realize a usable temperature control with the relatively coarse direct control on the coolant pressure yet. If necessary, short-term pressure peaks open the bypass branch 6bv However, it comes to thermal shock effects with inflow of very cold coolant from the previously closed radiator circuit yet, because the thermostat 6 this does not allow. Short-term pressure peaks are often damped away, ie the additional valve closes very quickly, without causing the thermostat to open 6 comes. This is in particular because with the opening of the additional valve 6bv the proportion of the coolant pump 7 ia directly decreases at the control pressure and in addition the local vapor bubble formation is reduced by the higher heat transfer coefficient.

Compared to known thermal management solutions, the thermostat 6 replace by a controlled by the engine control rotary valve with precise positioning and control using the engine coolant temperature and / or thermal models, the inventive method not only means a drastic reduction in component and application costs, but also a drastic gain in reliability. Even if alternative methods are used to detect motor control information regarding local component overheating and potential cavitation boundary conditions by means of coolant pressure sensors at the pump or motor exit, the adaptation of the metering accuracy and speed represents a much greater challenge than in the method according to the invention.

The same applies to all experiments, by means of pressure cans or similar, which directly on the rotary valve or Dehnstoffthermostaten 6 act and in particular are superimposed on the expansion behavior of the expansion element, a similar good-natured Si safety monitoring to realize as with the inventive approach. The probability that pressure spikes temporarily the cooler branch 6a unintentionally open is extremely high in these alternative methods and means in the best case only a loss of fuel consumption and heating comfort, because in addition heat is lost through the radiator or suddenly cold water at the heat exchanger 4 is applied. In the worst case, frequent thermal shock cycling can also reduce engine life.

Of the Comparison of the coolant pressure with the ambient pressure plus a biasing force or working directly with an absolute pressure can is a very serious alternative against this background to control by means of the engine control, especially because a easy retrofitting on existing engine cooling systems is possible.

Even if the free controllability of the additional valve 6bv with control via the motor control 20 Given the better tuning options, it promises slightly more fuel-saving potential, these extremely low costs of the directly pressure-actuated valve are very attractive.

As additional valves 6bv With direct control via the coolant pressure can be particularly cost-effective use of heating valves with vacuum actuators in which instead of the air vacuum, the coolant control pressure is applied to the original vacuum can, with adjustment of the biasing force such that the pressure and not the negative pressure leads to the movement of the valve body. A corresponding spring force can optionally in the membrane 101 be integrated, as in 10 , or it can be a spring on the membrane 101 act, so that the valve body 106 only when the atmospheric pressure is exceeded by a defined value of, for example, 0.4 bar opens.

Working under atmospheric pressure on one side of the membrane has the particular advantage of simplicity. Given the permissible range of pressure to open, the natural variation of the ambient pressure plays only a minor role. Especially in higher geographical positions, the valve opens a little earlier in view of the lower atmospheric pressure, which is quite desirable in view of the already somewhat more cold-critical mountain driving. If this ambient pressure effect is undesirable, however, it is also possible without difficulty to use an absolute pressure can, for example a defined absolute pressure of air plus a spring pressure force in one chamber on the diaphragm 101 acts and the coolant pressure 103 in the other chamber. The effort, for example, the ram 104 with an additional Gummifaltenbalg or similar To seal against the pressure chamber, while keeping within acceptable limits.

The process according to the invention can be particularly advantageously used in conjunction with an el. Auxiliary pump 2 with placement of the two heater heat exchanger connections upstream of the auxiliary valve 6bv and on the pressure side of the engine cooling water pump, either directly at the pump outlet or at the bottom of the water jacket of the cylinder liner. Corresponding examples are in 3 - 6 shown.

With additional valve closed 6bv ie closed bypass branch 6b and closed radiator branch 6a it turns a zero pressure difference at the heater core 4 as well as in the venting branch 9a and inside the engine 1 , This can be done by opening and closing the on / off additional valve 6bv connected with switching on and off the el. auxiliary pump 2 between fuel consumption-oriented settings with and without heating and a setting with high cooling demand with open additional valve 6bv switch. It is closed with additional valve 6bv and with closed cooler branch 6a in particular the direction of conveyance through the motor by means of reversal of the el. Additional pump freely selectable. The specific advantages coupled therewith - depending on the engine waste heat requirement and the heating power requirement for the driver's cab - and the associated additional fuel saving potentials with and without heating will be described in detail later using exemplary embodiments. And even if the el. Pump 2 should be saved, even with these arrangements, a part of the fuel saving potential of the method according to the invention can be implemented, because it is particularly possible to completely suppress the coolant flow through the engine by the additional valve 6bv closes and if necessary by opening the additional valve 6bv to switch to conventional cooling, heating and venting operation.

In order to further deepen the idea according to the invention, some particularly advantageous embodiments will be described in more detail below with reference to the exemplary cooling and heating circuits 2 - 6 described.

For this purpose, the embodiment according to 2 in particular the following components and properties:
The cooling circuit with internal combustion engine 1 includes, inter alia, a heating heat exchanger 4 , a double-acting expander thermostat 6 with bypass valve and radiator plate, engine coolant pump 7 , Additional valve 6bv , Oil cooler 40 , Engine control 20 , Out the same container 9 as well as vehicle cooler 8th ,

The focus here is initially on improving fuel economy with minimal changes to today's automotive market. In the simplest case, the changes are limited to laying the heating return to a position behind the expansion thermostat 6 and in front of the engine coolant pump 7 , the insertion of a low-pressure-loss additional valve 6bv , which is opened at increased cooling demand and optionally an adjustment of the flow rate through the heating heat exchanger, such that the flow through the heating branch 4a with additional valve open 6bv and closed radiator branch 6a only a fraction of the coolant flow in the bypass branch 6b is. This tuning is particularly advantageous in order to achieve fast response times in the transition to high cooling demand and to ensure a high quality control while maintaining the thermostat target temperature at high cooling demand. Too high a coolant throughput in the heater branch would inevitably lead to an increase in the effective thermostat nominal temperature at engine full load and with the heating switched off, because part of the circulating coolant does not enter the control loop of the expansion thermostat 6 is involved.

This is illustrated below by means of a numerical example: In the case of many engines, the cooling circuit is closed 6a the ratio bypass current 6b to heating current 4a in the order of 3.5 to 1. Depending on the engine operating condition, coolant temperature differences between engine inlet and engine outlet are up to 6K, sometimes even up to 10K and more. The admixture of coolant according to the invention downstream of the Dehnstoffthermostaten 6 For example, which is 10K warmer than the thermostatic opening temperature, the ratio of bypass coolant flow to heater coolant flow of 3.5 to 1 would have an effect of slightly more than 2K increase in the effective thermostatic opening temperature. Up to average specific engine power, this is still acceptable, but often already critical in high-performance turbochargers, so that a reduction of the heating-side coolant flow may have to be made for this engine type. This can already be done in the basic design of the heating branch, reducing the line cross-sections or by increasing the pressure loss in the heat exchanger or in combination with a heat from a technical point of view anyway particularly advantageous heat exchanger in countercurrent design.

The particularly advantageous embodiment of the heating circuit according to the invention such that when the thermostat is closed and the bypass branch is fully open, 80% or more of the engine-internal coolant throughput through the bypass branch 6b In particular, the user is freed from the need to apply a special vehicle-specific coordination strategy for this problem.

is already an additional one Valve in the heating circuit available, e.g. in vehicles with water-side control of the cabin heater or in the case of air-side regulation, the unwanted heating of the To prevent cabin air during operation without heating, that's how it is particularly advantageous for lowering the effective thermostatic opening temperature with this heater-side valve, the coolant flow in the heating branch to throttle or stop altogether.

The activation of the additional valve 6bv and optionally an additional valve in the heating branch, for example, by the engine control 20 done, which via the temperature sensor 20a determined the cooling demand. Optionally, a thermal model is also stored, which defines, for example, based on the integrated over the distance covered curves of engine load and engine speed and their instantaneous values, which mode of the additional valve 6bv is selected.

With additional valve open 6bv is the coolant according to 2 from the engine coolant pump 7 by the internal combustion engine 1 promoted and flows over the additional valve 6bv in the bypass branch 6b to the conventional expansion thermostat 6 , During warm-up, the radiator-side plate of the expansion thermostat closes the radiator circuit 6a while the bypass side plate is open. The vent line 9a of the expansion tank 9 is downstream of the additional valve 6bv connected. From the expansion tank, the coolant flows together with the water of the oil cooler return into the bypass thermostats 6 , As a conventional bypass thermostat 6 is used in conventional cooling systems usually used for the heating return line with open as closed thermostat 6 to the engine coolant pump 7 open. Upstream of the additional valve 6bv is the cooling water for the heating circuit 4a taken. The heating heat exchanger 4 is traversed at this setting in a conventional manner. As long as the additional valve 6bv In the open state, only a relatively small pressure loss generated, no further transformation of the components must be made to achieve the full heating power. Therefore, a rotary valve is preferably used as an additional valve, the full channel cross section of the bypass line in the open state 6b releases. Since the rotary valve is only operated on /, this is very simple and inexpensive to produce, most easily with a Va The vacuum actuator is one of the engine control 20 controlled solenoid valve is supplied with negative pressure.

During warm-up without cabin heating demand is at low to medium engine load, the additional valve 6bv through the engine control 20 closed. This is not just the bypass cycle 6b interrupted but also the ventilation circuit 9a , the cooler circuit 6a and the flow through the oil cooler 40 , With the coolant flow rate reduced to the flow in the heating branch, the water-side heat transfer coefficient in the engine decreases in a known manner and the coolant and component temperature in the engine increases. The reduction of friction by a warmer cylinder liner, slightly lower engine power the engine coolant pump, warmer oil and gasoline engines thermal Entdrosselung the intake air then ultimately lead to the characteristic fuel economy of this heat management measure. As long as suitable sensors or thermal models overheat the engine is ensured, the additional valve 6bv stay closed. Is because of too high pump speed with cavitation on the coolant pump 7 to calculate, so opens the engine control 20 the additional valve 6bv , Likewise if the thermal load is too high or at full motor load. The high actuating speed of the additional valve 6bv compared to the potential alternative "EI. Thermostat "considerably expands the range of motion until the first time the thermostat is opened, depending on the type of internal combustion engine, where various strategies are advantageous until the auxiliary valve is opened for the first time.

The simplest strategy is to wait as long as possible until the additional valve 6bv opens and the Bypasszweig together with oil cooler and the vent circuit incorporates and optionally opens the radiator circuit something. It may be advantageous for better ventilation, the first few seconds of warm-up still open with additional valve 6bv to work.

In particular, however, it may also be advantageous to use the additional valve 6bv initially keep closed, then to open the auxiliary valve when reaching a first temperature below the thermostat opening temperature, so that a first temperature compensation in the bypass and heating branch adjusts itself and the oil cooler 40 a heat transfer from the water to the oil sets. If necessary, the flow in the vent line must be additionally throttled by a permanently installed throttle point.

As long as no flow in the bypass branch 6b There is no risk that a part of the heated cooling water escapes through a partial opening of the radiator thermostat.

A sudden opening of the additional valve 6bv leads directly to an increase in the heat transfer coefficient in the water jacket of the engine and thus to a cooling effect. A thermal shock risk does not exist because the thermostat 6 with additional valve open 6bv ensures in a known manner a successive admixing of cold cooling water from the radiator branch.

Optionally, a clocked opening of the additional valve takes place 6bv , so that a gradual connection of the radiator is feasible. In this way, even when heat dissipation through the radiator 8th realize increased component temperatures.

In this case, the inventive method according to 2 not claiming to be the thermodynamically best way. Rather, the ratio of costs to benefits can always be seen here. Especially if the fuel consumption without additional demands on the heating effect in the foreground, the inventive method is already without the use of special heat exchangers for lower flow advantageous.

Closing the additional valve 6bv causes depending on the delivery characteristics of the engine coolant pump 7 a certain pressure increase and thus increased coolant flow through the heater core 4 , Previous efforts in a wide variety of patent applications have focused on bringing about an improvement in heater core efficiency. However, both the pressure gain and the improvement of Heizungswärmetauscherwirkungsgrades is generally comparatively low and justify the cost of the additional valve by itself 6bv hardly likely. In addition, it has since been shown that it is often more favorable in the overall system, even with a focus on better heat output in warm-up and heating power deficit, to operate the heater core with lower flow to minimize heat loss to the environment.

If at the same time an improvement of the heat output is required, then it is based on 2 particularly advantageous, the additional valve 6bv to close at the same time make a throttling of the coolant flow rate through the engine and the heater core where the heater core is preferably designed in countercurrent construction.

3 shows a particularly advantageous embodiment of the method according to the invention with an el. auxiliary pump 2 in the heating branch.

The cooling water for the heating circuit 4a is here behind the engine cooling water pump 7 or taken in the lower part of the water jacket in the engine block and flows with the auxiliary valve closed 6bv and closed radiator circuit 6a over the cylinder head back to the cylinder block, ie the el. auxiliary pump 2 inverted with closed additional valve 6bv the flow direction of the motor 1 , This inversion of the flow is particularly advantageous when the heating heat exchanger 4 Heat must be removed for heating purposes or when operating without heating after initially standing cooling water homogenization of the engine temperature is required. Cold water zones in the especially friction-resistant water jacket area along the cylinder liner are thus extracted, cold cooling water fed back into the engine is preheated on the cylinder head which is less sensitive to cold friction surfaces.

When opening the additional valve 6bv promotes the el. auxiliary pump according to 3 the coolant with the assistance of the engine coolant pump 7 through the heating heat exchanger 4 , The flow direction of the engine is now again from block to head, as the high flow rate of the engine coolant pump 7 the direction of flow is determined. Especially for applications with a countercurrent heat exchanger and a particularly low coolant volume flow in the range of 2 l / min and less, with comparatively low el. Drive power of the el. Auxiliary pump, it is easiest to simply allow the el. Pump to continue running. Specifically, the design for relatively low coolant flow through the heater core ensures that the heater coolant flow not promoted by the entire engine does not result in a full load cooling deficit of the engine.

It is particularly advantageous according to this embodiment 3 in that the conveying direction of the el. pump 2 with additional valve closed 6bv and closed cooler circuit depending on the requirements for heating, cooling and hot cooling can be reversed. Especially with positive displacement pumps and axial impeller pumps, this can be done simply by reversing the pump rotation direction, as in 4 shown.

With regard to the potential cost savings when using already available serial components, it is also quite possible, both el. Additional pump 2 no redesign to use. In order to realize fuel consumption advantages with particularly inexpensive conventional motor vehicle heating pumps, in particular with radial impeller pumps, the reversal of the flow direction from inverted engine flow to normal engine flow in an arrangement according to 3 by opening the bypass valve 6bv at the same time switching off the el. auxiliary pump 2 very easy and inexpensive.

These embodiments of the method according to the invention 3 or in the reverse direction of the el. Pump in 4 make it possible to realize with minimal component expenditure both standing cooling water inside the engine as well as a flow from the head to the block as well as the flow from the block to the head. In conjunction with the el. Control of the el. Additional valve and the el. Auxiliary pump by means of the motor control 20 In addition, a largely free adjustability of the coolant or engine component temperature results. The cost / benefit ratio in relation to the achievable fuel consumption advantage is thus much cheaper than previously known thermal management measures. In addition to the fuel consumption advantage with and without heating come in conjunction with the heating performance-oriented supplementary measures further benefits through improved heating and possibly eliminating the cost of additional heating.

If especially for vehicles of the upper price range many times anyway an el. Heating pump is used to stand at a stationary internal combustion engine by circulation of coolant to ensure or maintain a maintenance of the cabin heater Cooling the turbocharger after the engine has been stopped, the cost / benefit ratio is still improving further.

It has a cost-reducing effect, in particular, when switching the conveying direction to normal operation by simply switching off the el. Auxiliary pump 2 can be realized, since then the life requirements of the auxiliary pump can be significantly lowered. Available low-cost heating or turbocharging pumps with simple brush motors are already sufficient here.

As already described, both the embodiment according to FIG 3 as according to 4 the setting of stationary coolant, if the el. auxiliary pump 2 simultaneously with the closing of the additional valve 6bv by means of the control 20c is turned off. This embodiment of the system according to the invention offers the very special advantage that it allows one hand to work with stagnant cooling water, but on the other hand with - compared to the open bypass branch - small amounts of circulating cooling water. This is particularly advantageous for operating situations with heating, since now advantages in terms of fuel consumption and heating effect can be achieved. In particular, it is also possible to increase the coolant temperatures by switching on the el. Auxiliary pump in the course of warming without the risk of local overheating to a somewhat elevated level ben. This applies to the integration according to 3 as well as for the arrangement according to 4 in reverse flow direction. In both cases, there is no risk of the radiator being opened unintentionally when the heating heat exchanger flows through, because warm coolant flows along the thermostat 6 flows. In addition, the integration offers according to 3 the advantage that when the additional valve is closed 6bv a flow of the engine from the head to the block takes place. This brings fuel economy benefits when connecting the initial cold heating circuit and especially when removing heat from the heater core. These advantages are due to the fact that in view of the tribological requirements in the cylinder head cold coolant is less harmful than in the cylinder bore. Another advantage arises from the fact that possibly sinking cold water does not stay down in the water jacket but is sucked off.

Conversely, especially with increased demands on the heating normally the embodiment according to 4 slightly cheaper, as the cylinder block and the crankshaft / oil sump area are heated slightly less. This is especially true when integrating the oil cooler 40 according to 6 where the at the heat exchanger 4 Cooled cooling water extracts additional heat from the oil. Especially at relatively low flow through the heating heat exchanger, the amounts of heat transferred here in the direction of better heating effect are quite significant. The integration downstream of the engine coolant pump 7 has the special advantage that when the additional valve is closed 6bv the flow through the engine very easily between the state according to 5 and 6 can be switched, ie it can be easily switched between a heating power-oriented and a more fuel consumption optimized mode. It suffices for this purpose a simple reversal of the el. Auxiliary pump 2 , For this purpose, it is particularly advantageous, the auxiliary pump 2 as a gear pump, G-rotor pump or axial impeller pump to design, because in these pumps, in principle, a reversal of the conveying direction is very easy. As long as the additional valve 6bv remains closed, is the required pressure of the el. auxiliary pump 2 for both directions of flow through the heating heat exchanger approximately equal. It does not matter how fast the engine coolant pump gets 7 rotates. This considerably simplifies the implementation of flow control strategies by the engine or by the heat exchanger, which is very helpful both for operation in the direction of better heat output and also for operation in the direction of better fuel consumption.

A flow strategy for the simultaneous improvement of heating power and fuel consumption using the refrigeration cycle according to 6 and 5 could thus be designed particularly advantageous, for example, as follows:
For a cold start at -10 ° C ambient temperature and 50 km / h, ie at rel. low engine load, in a first step, the additional valve 6bv closed, the el. auxiliary pump conveys the coolant in the in 6 shown direction. For a secure defrosting of the windshields is ensured or fogging of the discs is avoided. After reaching a minimum coolant temperature, the fan power is then increased gradually, so that the air mass flow into the cab increases, while the air flow is now no longer primarily directed by the defroster, but also in the direction of the footwell and possibly in the direction Mannanströmer.

In this case, it is advantageous for maximizing the cabin heating effect when the coolant mass flow through the heating heat exchanger 4 is adjusted so that the coolant temperature at the outlet noticeably below the oil temperature of the oil cooler 40 flowing engine oil is. The better the degree of heat utilization of the heating heat exchanger at relatively low coolant flows, the more heat can be obtained on this detour via the cooling of the engine oil for heating purposes. The reduced heat losses to the environment overcompensate for losses of heater heat exchanger efficiency with reduction of the cooling gas throughput, with careful tuning of coolant center volume flow and heater core efficiency. For maximum heating power, it is particularly advantageous to use countercurrent heat exchanger, since they have much lower efficiency loss in reducing the coolant throughput than conventional cross-flow heat exchanger.

When the desired interior temperature is reached in the cab, the air-side damper prevents 5 in that the interior temperature in the vehicle continues to rise by adding a portion of the fresh air delivered to the cabin to the heat exchanger 4 passed by.

Thus, the coolant temperature rises at the Heizungswärmetauscheraustritt and the oil is less or no heat removed. In the further course of the journey, in general, the coolant temperature will continue to rise, especially if the amount of heat taken off at the heating heat exchanger, in the case of a warm interior, additionally decreases by a reduction in the fan power. But even if the coolant with temperatures above the thermostat opening temperature, for example, 88 ° C from the heater core and the oil cooler flows back to the engine, the thermostat 6 closed, because the coolant is not along the Dehn material element flows. This will ensure that there is no unintentional heat over the radiator 8th is discharged before a complete warming of the engine including the cooling water and the oil has occurred.

Optionally, the el. Pump 2 be increased after reaching the desired interior temperature in the flow rate to increase the heat input into the engine oil thereby that the cooling water arrives warmer at the oil cooler and at the same time there is a slightly better heat transfer coefficient within the oil cooler. This is also advantageous because it is desirable to achieve a more homogeneous temperature distribution within the engine as it approaches critical component temperatures or the critical cooling system pressure.

As soon as the engine load or the coolant temperature or the component temperature or the coolant pressure exceeds a critical value, the additional valve opens 6bv ,

This immediately flows a very high flow of coolant through the bypass branch 6b and through the engine and ensures a temperature compensation. If necessary, the expansion element of the thermostat, now flowed around by warm coolant, opens 6 the cooler circuit 6a and regulates to the thermostat target temperature of eg 88 ° C. In many cases, it will be advantageous in terms of optimum fuel economy, the additional valve 6bv to close again after a short time, since the heat-active masses in the expansion tank and in the bypass branch already enough to dampen thermal load peaks. Optionally, an on / off control may still use some fuel economy benefit because the time average engine coolant temperature is thereby above the thermostat opening temperature.

With additional valve open 6bv it is according to the application 6 important that the el. auxiliary pump 2 is able, even against the pressure difference, that of the auxiliary valve open 6bv very high coolant flow rate through the engine to the heating heat exchanger circuit 4a imprints to promote. But this can be achieved with relatively little effort, especially since the el. Auxiliary pump only relatively little has to promote coolant through the heater.

The previous versions too 6 In particular, they focused on the task "Best heating effect" 6 by simply reversing the el. auxiliary pump to the circuit according to 5 be switched and then work as a fuel consumption optimized system. This is always of particular interest when the requirements of cabin heating are relatively easy to meet, ie with low heating demand or excess engine heat. Even if in such operating situations already without reversal of the el. Auxiliary pump 2 Fuel savings can be realized, so the polarity reversal leads to an additional frictional advantage, since now the cold coolant first flows through the cylinder head and preheated reaches the water jacket of the cylinder bore. Further frictional benefits result from the extraction of cold cooling water zones in the lower region of the cylinder bore and the homogenization of the coolant and oil temperatures in the oil cooler 40 ,

With increased cooling demand also opens according to this application 5 and 6 the additional valve 6bv and ensures safe heat dissipation through the radiator 8th , In the particularly advantageous application with el. Impeller auxiliary pump 2 can be dispensed with in this mode, where appropriate, the el. Drive, as this runs freely in the presence of the applied pressure gradient and the low coolant viscosity at high coolant temperatures or flows through it. This protects the el. Auxiliary pump.

The arrangement according to 5 and 6 offers here the very special advantage that even in the event of failure of the el. impeller auxiliary pump 2 even the usual today heating comfort can be realized by simply the additional valve 6bv is opened.

additional valves 6bv for carrying out the method according to the invention are already available on the market. Particularly preferred here are simple on / off valves with vacuum can or magnet as an actuator.

An additional safeguard or monitoring of the valve position is in view of the already existing monitoring of the cooling water or component temperature by means of the engine control 20 not really necessary. This applies in particular if the valve position "open in the event of failure of the actuator energy" is selected as the basic setting, which is possible with no costs for magnetic or vacuum actuators.

Nevertheless, especially as redundant protection in the first series applications, an additional valve with safety expansion element 6BS particularly advantageous, as in 7 shown as an example. Here the line controls 63 the electromagnet 6BF on and opens at el. energizing the plate 6bv against the force of the spring 62 , If at high engine speed too much negative pressure, so the plate 6bv absorbed. Likewise, the plate opens 6bv if the stamp 66 of the security expansion element 6BS exceeds its limit temperature of for example 105 ° C. This security functionalities are shown here exemplarily on a poppet valve. In an analogous way, however, these can also be realized on a rotary valve or roller or ball valve with external lever mechanism. If necessary, the expansion element then has to protrude slightly into the cooling water or a throughflow of cooling water connection to the expansion element is to be produced.

Particularly advantageous in this context is the embodiment according to 8th in which instead of an expansion element one of a characteristic cooling water pressure with the line 69 acted upon actuator 6BX via a reciprocating piston or a membrane with plunger 66 the pressing on reaching a critical state autonomous, ie override the engine control takes over. It is essential here that the side of the membrane or the reciprocating piston which counteracts the coolant pressure is acted upon by a spring force and / or pressure such that the system does not act until it has a control pressure 69 reacts, which is sufficiently above the atmospheric pressure. Control pressure values between 1.3 and 1.8 bar absolute pressure have in today's cooling systems with opening pressures of the pressure lid on the expansion tank 9 of usually 2.4-2.6 bar absolute pressure shown to be well suited.

At the valve according to 8th In particular, there is the advantage that the installation position is relatively freely selectable. The preferred position of the pressure extraction is the vicinity of the engine coolant pump outlet or the engine block, but also positions at the exit from the engine head can be used with appropriate fine tuning. As a special feature, in this embodiment, not a local temperature, as already detected, for example, by the coolant temperature sensor of the engine control anyway, used for redundant protection, but an integrating signal. As soon as steam bubbles are produced at sufficient points of the cooling system with cooling water at any point of the engine, the associated increase in the pressure of the pressure tapping point is impressed and leads to the opening of the additional valve when a critical value is exceeded 6bv , This dichotomy of the monitoring principles with the temperature sensor of the engine control and the self-sufficient actuator with pressurization reduces the risk of retrofitting into already largely finished cooling circuits to a minimum. Especially in the variants with flow through the engine from head to block or in variants with switching the flow direction, the risk of error is drastically reduced.

In a further step shows 9 an auxiliary valve that is no longer on the engine control 20 is driven, but directly from a piston, with a characteristic pressure 69 the cooling water circuit is acted upon.

If a maximum permitted coolant absolute pressure is exceeded, the flow path is here 67 . 68 opened for the bypass branch. Although a part of the fuel economy savings potential is given up, since an optimal adjustment of the opening pressure is not possible for the entire map range of the engine, the engine cooling and the heating demand, but the benefits in terms of heating remain as far as possible.

This is offset by the elimination of the solenoid valve at Vakuumaktuator or by the elimination of the solenoid in directly controlled cooling water solenoid valve almost a halving the cost. This is especially true of the valve design according to the invention 10 clear:
The self-sufficient additional valve works here with a rotary valve 106 , over the lever 105 and the pestle 104 the external pressure box 100 is driven. The coolant pressure reaches via the connection 103 in the pressure box and opens when a setpoint is exceeded, the valve against the atmospheric back pressure plus a biasing force. A considerable advantage is given by the fact that it is possible to make the rotary valve so that the pressure losses almost to the losses of the pipe flow of the inlet and outlet 67 and 68 to reduce. This makes in particular the subsequent system integration of the additional valve 6bv very easy. But even more important is the advantage that can be used in this actuator already proven production equipment and tools of today's series applications. The valve costs are thus extremely low and yet provide both the functionality of closing in warm-up and the simultaneous safety monitoring against overheating of the engine and the cavitation of the engine coolant pump. Even lower are the costs if the control pressure is directly at the valve 6bv upstream of the valve body 106 is removed, as in 13 shown. This can often be achieved in particular without problems if only a moderate pressure drop occurs within the internal combustion engine and the bypass or radiator hose.

The control via a characteristic coolant pressure is promoted in particular by the fact that the integration of the return from the expansion tank 9 to the thermostat 6 or to the engine cooling water pump 7 always open, as in 1 - 6 shown. A connection of the return on the cold side of the cooler would be more problematic here, since the system pressures then move more with open and closed thermostat. The integration of the vent line according to the invention 9a behind the additional valve 6bv as well as the Return from the expansion tank 9 So not only helps an increased risk of cavitation of the engine coolant pump 7 and to avoid the heat losses of the vent circuit in the warm-up phase, but it is also helpful on the way to an extremely inexpensive additional valve hardware to improve fuel consumption and, where appropriate, the heating power.

In the vast majority of applications of the method according to the invention a simple open / close valve control of the additional valve is sufficient 6bv , This is partly due to the fact that during warm-up and in a wide part-load working range already the heat-active masses of the internal cooling circuit and the heat removal at the heat exchanger ensure that the engine does not overheat. On the other hand, however, the immediate response of the cooling effect in the sudden opening of the additional valve, long before the radiator circuit opens. A very rapid heating of the expansion element leads at full flow of lying at well above the thermostat opening temperature cooling water in the suddenly opened bypass branch but possibly also quickly to the desired at longer full load lowering the coolant temperature.

Will replace the activation of the additional valve 6bv via the engine control 20 the variant of the invention with self-sufficient additional valve 6bv used, in particular with direct pressurization of the actuator, eg with an additional valve according to 10 , Part of the margin is lost in terms of fuel economy by the fact that a little more time is required for the switching especially at slow heating or that something more safety distance to the critical system pressure must be maintained. In return, not only the costs fall dramatically, a part of the disadvantages is compensated in particular by the fact that the pressure-based management of the bypass valve settings with partially opened radiator and especially operating situations with increased engine part load controls very well and in these operating situations still for an elevated component temperature level of the friction-related jobs in the engine. Although this is in principle possible with the on / off control of a vacuum valve or solenoid valve by the engine control, but this results in a somewhat increased vehicle-specific application effort of the engine.

Against this background and the interactions of the direct coolant pressure actuation of the actuator described in detail above, the self-sufficient valve is in accordance with 10 quite an attractive alternative to the system with activation of the additional valve 6bv via the engine control 20 ,

In addition to the specific application of the valves according to 9 and 10 in the bypass branch 6b in one of the methods according to the invention, these can also be used very safely and cost-effectively for switching off or switching on individual branches in the cooling system of any internal combustion engine with liquid coolant-quite separately from the method according to the invention. This is always the case, in particular, when the vapor bubbles produced when a setpoint temperature is locally exceeded produce a sufficiently high coolant pressure above the atmospheric pressure, so that the actuator engages the valve body 106 shifts or if already a circuit with increased engine speed and thus with increased engine coolant pump pressure is sufficient or desired.

Potential applications are, for example, the shutdown of the expansion tank on its own, ie without simultaneous involvement of the bypass branch 6b , with the valve directly into the venting branch 9a is installed and wherein the coolant pressure for driving the actuator is removed at the engine outlet. So it is already advantageous in view of the low cost of such a self-sufficient working valve when the valve only the return of the expansion tank 9 closes and so for a faster warm-up with initial inhibition of the flow through the expansion tank 9 provides. Starting from 1 would that mean, for example, that the additional valve 6bv eliminates and that a directly controlled by the pressure valve in the return from the expansion tank 9 to the thermostat 6 is arranged. Due to the extremely low cost, this measure is still advantageous, a solenoid valve or a valve with vacuum actuator would be too expensive here compared to the recoverable benefits in terms of warm-up. An initially conceivable as a cost alternative valve with Dehnstoffaktuator would have in this application the generally unacceptable disadvantage that it would remain closed for a long time or even permanently when filling the cooling system in the service and in contrast to the valve according to 10 could not be opened by increasing the engine speed.

The low costs allow this quite to use several pressure-controlled valves, optionally with staggered opening pressure levels, in particular, the low pressure loss of the variant according to 10 ensures that no disadvantages in the open state are to be expected.

Such an application would be, for example, the integration of the oil cooler 40 parallel to the heating heat exchanger 4 wherein the oil cooler is closed in warm-up in view of the lack of pressure and at increased engine speed and / or local vapor bubble formation at high system temperature or high system pressure opens. This configuration would be in both cooling systems with bypass thermostat 6 as well as with single thermostat 6 advantageous because initially the engine and the cooling water are heated faster and yet later the oil cooler is involved. In addition, such a valve allows it, especially the most interesting applications with reduced coolant flow through the heater core 4 , without risk to engine life even with coolant systems without bypass branch 6b to be used, as they are still partially used in engines of relatively low specific power.

Also in these applications, it is advantageous for cost and functional reasons, if the with the coolant pressure 69 acted actuator when a maximum permitted coolant relative pressure relative to the atmospheric pressure exceeds the flow path 67 . 68 opens through the valve.

But also working on absolute pressure basis, i. with locked second chamber of the pressure box under defined gas and spring pressure is analogous to the statements already made above possible with little extra effort.

Also if the actual scope of the inventive method and devices primarily switching at coolant pressures above of the atmospheric Pressure and prefers with the misused conventional Vacuum canister relative to atmospheric pressure plus one Preload works, can be if necessary also an opening with the help of the described absolute pressure box. or closing pressure of the coolant below the atmospheric Realize pressure. If necessary, this also allows earlier switching points at lower coolant temperature or realize at lower engine load or lower engine speed.

The particularly preferred use of the inventive concept in conjunction with countercurrent heat exchangers with low flow rates provides for heat extraction for cabin heating in particular also benefits in terms of thermal stratification of the air at the heat exchanger outlet. Even when in heating mode with conventional cross-flow heating heat exchangers in view of a sufficient cabin temperature throttling the coolant flow rate through engine and heater core would be desirable to save fuel, this would often be a very uneven air temperature behind the heating heat exchanger result, coupled with corresponding problems, especially in multi-zone air conditioners with air-side cabin temperature control.

at high heat extraction reinforced This effect is still, and in addition, the efficiency of the heating heat exchanger at throttling the coolant flow rate strongly breaks down and thus a high coolant flow through the Heater core imperative is. This means in conventional cross-flow heating heat exchangers, that a fuel consumption optimal operation with reduced coolant flow rate both during warm-up and when the engine is largely warm At least when switched on cabin heating is only very limited. This disadvantage thus already occurs in driving situations at which actually quite enough waste heat for the Heating available is worse, but still, as soon as a very large heating power is removed at low engine load.

Especially the designs with el. Additional pump 2 open here the ability to adjust the coolant flow through the heater core by means of variable el. drive power so that depending on the heat output even with cross-flow heat exchangers on the one hand no problems with the thermal stratification, but on the other hand, an approximately fuel consumption optimal operation with the smallest possible coolant throughput through the engine is feasible , Especially with closed additional valve 6bv this is particularly easy to implement because the el. coolant pump 2 largely independent of the engine coolant pump 7 determines the throughput.

Especially in connection with the use of countercurrent heat exchangers 4 and / or means for limiting the flow through the heating heat exchanger 4 exists in the inventive method with additional valve 6bv in the bypass branch 6b in particular, the possibility of even with already in the series expansion thermostats 6 to leave the heating return in the usual place, if the flow limitation in the heating branch ensures that the flow is so low that the vent branch 9a with additional valve closed 6bv no sufficient pressure difference is impressed to effect its flow. In 11 this is exemplified by the fact that as el. auxiliary pump 2 a gear pump is used with a largely constant speed, which limits the coolant throughput even at high engine pump speed to values around 2 l / min. This ensures, except for slight thermosiphon effects, that despite the cavitation insensitive integration of the expansion tank 9 during warm-up, only an admixture of coolant from the expansion tank takes place when the additional valve 6bv is opened. Compared to the supply of the heating return downstream of the thermostat 6 are with this involvement the fuel saving potential and also the Heat output is generally slightly lower, as a larger heat-active mass must be heated and there with little or no heat removal from the thermostat 6 opens earlier. Nevertheless, this application is of particular interest when already available serial components are to be used. In addition, this embodiment has the advantage that, if appropriate, an increase in the coolant throughput in the heating branch or lower heat removal at the heating heat exchanger can also be used to set a partial opening of the thermostat. It depends on the particular engine cooling system, whether it is cheaper, the operating state with partial heat dissipation on the radiator 8th via a cycle of the additional valve 6bv to approach or via a variation in the Heizungswärmetauscherdurchfluss. As an additional advantage of this embodiment, the fact is to mention that it is also in case of failure of the additional valve 6bv in the closed position even when the air side shutdown of the heater gives the opportunity to continue with reduced cooling capacity. It is up to the user to what extent he uses conventional solenoid valves or vacuum valves from ongoing mass production and, where appropriate, implemented such a fail-safe strategy or whether he equal to the additional valves according to the invention 6bv resorting to the detailed safety features against potential overheating, in which a standing position in the open position is actually not possible, as long as there is cooling water in the system.

The previous description of the process variants and devices according to the invention, taking into account the benefits of hot cooling in the partial load and the division of tasks with respect to safe switching from hot cooling to normal or full load cooling with a pressure-operated valve 6bv on the one hand and the regulation of the cooler performance with a self-sufficient expansion thermostat 6 on the other hand, based on exemplary applications, in particular in conjunction with a particularly advantageous integration of the venting branch 9a , However, the inventive concept is also quite generally applicable advantageously for methods and apparatus for operating cooling and heating circuits for motor vehicles with internal combustion engines with coolant-loaded thermostatic valves for controlling the radiator performance. An inexpensive as well as safe monitoring of the hot cooling with very high control quality with increased cooling requirements results in principle by the fact that a coolant pressure-actuated first valve 6bv upon exceeding an upper limit value for the coolant absolute pressure or the coolant relative pressure relative to a pressure outside the cooling system, a control coolant flow through the coolant-temperature-actuated thermostatic valve 6 releases, so that this heat dissipation through the vehicle radiator 8th to temperature values close to the thermostatic temperature. In particular, a mixture of the control coolant flow with the radiator flow before or on the expansion element of the thermostat 6 , so that sets a mixing temperature near the Thermostatnenntemperatur at least for correspondingly high control coolant flow for both Zumischpositionen, ie the autarkic thermostat removes from the Kühlerzweig only as much cooled coolant, as is currently required to cool the engine near the Thermostatnenntemperatur of, for example, 88 ° C. , This ensures in particular that a hypothermia or even a thermal shock risk for the engine does not arise. A direct operation of a radiator valve by means of the coolant pressure would compared to this detour via the thermostat 6 do not lead to an acceptable coolant temperature control, since the control would inevitably lack the information about the radiator temperature or the cooling potential of the radiator. Conversely, today's conventional cooling systems with conventional Dehnstoffthermostaten but also thermal management systems with three-liter thermostat not only lack the integral pressure information regarding local component overheating and possibly cavitation due to high pump speed, but generally also a sufficiently fast response of the actuator.

In the integration of the control current certain design guidelines are to be considered, as they are already partially described above. It is particularly simple and safe when the control current at least in phases with very high cooling potential of the vehicle radiator 8th and high cooling requirement of the internal combustion engine 1 at least that is great, that in the internal combustion engine in conjunction with not by the thermostat 6 Guided coolant branches sets an approximately homogeneous coolant temperature, so that in particular when the control current is open, less than 10 K coolant temperature difference between inlet and outlet result in the internal combustion engine. This ensures, in particular for partial load and full load, that the thermal stresses in the engine remain low.

Especially when the lowest possible coolant temperature for the internal combustion engine is required, it is advantageous, the control current so along the temperature-sensitive region of the thermostatic valve 6 to cause it to hit directly on the expansion element. This removes a little more cold coolant from the cooler than with homogeneous mixing. Conversely, with good mixing, especially when the mixture is already upstream of the expansion element, a slightly lower total volume flow can be realized by the internal combustion engine and it results a slightly better control quality with slightly improved fuel consumption. In particular, with good mixing upstream of the expansion element to set up relatively gentle transitions especially at slow as well as rapid opening of the control current.

For cost reasons, but also for a particularly simple and safe application, it is particularly advantageous if the coolant pressure-actuated first valve 6bv is actuated by an acted upon directly by the coolant pressure actuator and thereby causes the control current through the thermostatic valve. If the opening pressure for the additional valve, for example, set to relatively conservative 1.5 bar absolute pressure and the opening pressure of the pressure lid in the expansion tank at the today in many applications to find 2.4 bar absolute pressure, so is quite a fuel consumption relevant bandwidth ensured in the one also drives at fluctuating engine speed in the field of hot cooling. There is no risk of overheating given the relatively low valve opening pressure of 1.5 bar. Even with a certain loss of cooling water, ie when the air / vapor volume of the expansion tank increases and thus in particular causes a somewhat delayed control characteristic, such a system is still reliable. Optionally, however, the information of the coolant level sensor can be processed by the engine control to hedge.

Also if at high heat extraction the temperature at the heating return in the lower part load drops sharply and, where appropriate, during stationary driving at a very small heat exchanger volume flow below the thermostat opening temperature lies and a relatively high coolant temperature increase to Engine exit sets, opens The system sure once local steam bubbles inside the engine form. A sudden transition too high engine power arises from this operating condition No problem, since the additional valve is also here the vapor bubble formation or the increased engine coolant pump pressure opens at elevated speed.

Even if in today's internal combustion engines instead of the usual Water-glycol mixture accidentally pure water in the cooling circuit filled is, such a system is still reliable. The higher vapor pressure in the cooling system then leads only to an earlier opening of the Additional valve.

These compatibility in terms of the individual tolerances and the operating fluctuations of the individual Influence parameter is a very significant advantage of the method according to the invention.

In return for direct valve actuation, however, the advantages according to the invention can also be realized with an actuator indirectly acted upon by the coolant pressure. In this case, the indirect coolant pressure actuation takes place by means of a pressure sensor via an evaluation unit, in particular the engine control 20 that drives the actuator of the coolant pressure actuated first valve. The advantages of the free control are in particular the ability to adjust the hysteresis during opening and closing and make a refined and possibly additionally map-based control with respect to the heating power and fuel consumption. Since for various reasons monitoring of the coolant pressure would be desirable anyway, including redundant level monitoring, fall in such applications, the cost of such a pressure sensor not in the weight but only the additional cost of the separate actuator including its control by the engine control.

The advantages of the procedure, which draws the sum of system pressure and superimposed engine coolant pump pressure on the pressure actuation of the control valve, with regard to operational safety have already been described in detail. The system can - connected with a certain additional effort - but also be operated with the coolant system pressure alone, if correspondingly sensitive pressure sensors are used in conjunction with engine maps or if sensitive absolute pressure can be used, which in particular in the range around 1.0 bar coolant absolute pressure sufficient power reserves apply for direct pressure operation. The pressure extraction could then in particular in the expansion tank 9 take place where the air / vapor volume lying above the water performs an attenuation of the resulting pressure fluctuations over the engine speed fluctuations. The safety aspect that the valve at high engine power inevitably and immediately switches to increased cooling power when setting an increased engine speed, would thus be lost, in return, however, the result of the advantage that is driven with appropriate dimensioning on average over time in hot cooling mode. Especially at rel. cavitation-insensitive engines and engines with not to the last exhausted cooling reserve, in particular with rel. This is of particular interest, given the large full load coolant temperature difference across the engine.

Claims (39)

Method for operating a cooling and heating circuit for motor vehicles with an internal combustion engine 1 by means of an engine coolant pump 7 circulated coolant is cooled with a self-sufficient thermostatic valve 6 , which for controlling the coolant temperature, the coolant flow rate through the internal combustion engine 1 and the vehicle radiator branch 6a governs, with a bypass branch 6b which additionally varies the coolant flow rate through the internal combustion engine as a function of its cooling requirement, a heating branch 4a and a vent branch 9a , In particular, method for operating internal combustion engines with a conventional Dehnstoff thermostat, characterized in that the vent circuit 9a his water downstream of an additional valve 6bv removes which the coolant flow in the bypass branch 6b varies and in particular from the electronic engine control 20 is controlled, and that the vent circuit feeds its cooling water at a point upstream of the engine coolant pump into the cooling system, which in each position of the self-sufficient thermostatic valve 6 to the engine coolant pump is open. A method according to claim 1, characterized in that the closing of the additional valve 6bv during warm-up, the coolant flow through the expansion tank 8th in derogation. Method according to one of claims 1-2, characterized in that the closing of the additional valve 6bv reduces the total coolant throughput by the internal combustion engine or completely prevents their flow. A method according to claim 3, characterized in that only the closing of the additional valve 6bv reduces the total coolant throughput by the internal combustion engine or completely prevents their flow. Method according to one of claims 1-4, characterized in that the closing of the additional valve 6bv the total coolant flow rate through the engine in conjunction with a shift of the low pressure side heater connection to the high pressure side of the engine coolant pump 7 reduced or prevented. Method according to one of claims 1-4, characterized in that the closing of the additional valve 6bv the total coolant flow rate through the engine in conjunction with a restriction or shut-off valve in the heater branch 4a reduced or prevented. Method for cooling internal combustion engines, in particular using features according to one of claims 1-6, characterized in that the heating heat exchanger circuit 4a and / or others even when the thermostatic valve is closed 6 flow through coolant branches such downstream of the thermostatic valve 6 integrated into the cooling system are that the thermostatic valve 6 with additional valve closed 6bv undergoes such a low heat input that this remains closed well beyond the thermostat nominal temperature, and that the thermostatic valve 6 with additional valve open 6bv due to the flow through the coolant flow in the bypass branch 6b opens with its nominal temperature. Method according to one of claims 1-7, characterized in that the coolant for the heating heat exchanger circuit 4a upstream of the additional valve 6bv taken and between thermostatic valve 6 and engine cooling water pump 7 is fed again. Method according to one of claims 1-7, characterized in that the coolant for the heating heat exchanger circuit 4a from an el. auxiliary pump 2 upstream of the additional valve 6bv taken and downstream of the engine coolant pump 7 is fed again. Method according to one of claims 1-7, characterized in that the coolant for the heating heat exchanger circuit 4a from an el. auxiliary pump 2 downstream of the engine coolant pump 7 taken and upstream of the additional valve 6bv is fed again. Method according to one of claims 9-10, characterized in that the el. Auxiliary pump 2 when opening the additional valve 6bv is turned off. A method according to claim 9-10, characterized in that the el. Auxiliary pump 2 a reversal of the conveying direction of the coolant by the internal combustion engine 1 against the conveying direction of the engine coolant pump 7 causes, in particular when the additional valve is closed 6bv and low engine load is used to save fuel. Method according to one of claims 1-12, characterized in that the self-contained thermostat 6 by keeping the additional valve closed 6bv at least temporarily due to the lack of flow of the actuator is completely or partially prevented from opening, and thus the engine coolant temperature of the engine control 20 is freely adjustable. Method according to one of claims 1-13, characterized in that an oil cooler downstream of the additional valve 6bv is arranged and flows through only when opening the additional valve. Method according to one of claims 1-14, characterized in that by means of reverse rotation of the el. Auxiliary pump 2 , a reversal tion of the flow direction by the internal combustion engine 1 takes place and in particular that an axial pump is used, which causes the reversal of the flow direction by reversing the direction of the impeller. Method according to one of claims 1-14, characterized in that by closing the additional valve 6bv and simultaneous operation of the el. auxiliary pump 2 a reversal of the flow direction by the internal combustion engine 1 he follows. Method according to one of claims 1-13 or 15-16, characterized in that an oil cooler 40 in series with the heating heat exchanger 4 is arranged. Method according to one of claims 1-17, characterized in that by the reversal of the conveying direction by the internal combustion engine 1 is switched between a fuel consumption-oriented and a power-oriented mode. Method according to one of claims 1-14 or 1-18, characterized in that instead of the activation of the additional valve 6bv by means of the engine control 20 a self-sufficient control of the additional valve 6bv , in particular based on the refrigerant pressure occurs. A method according to claim 19, characterized in that the coolant pressure directly to the actuator of the additional valve 6bv acts. Method according to one of claims 19-20, characterized in that the coolant pressure in a region of high static pressure, in particular in the vicinity of the engine cooling water pump 7 or is taken in the cylinder block. Method according to one of claims 19-21, characterized that the coolant pressure directly acting on an actuator, its driving force from the pressure balance between the coolant pressure and a biasing force, in particular the counteracting atmospheric Pressure plus refers to a biasing force. Device for cooling and heating motor vehicles, in particular device for carrying out one of the methods according to one of claims 1-22 for operating a cooling and heating circuit for motor vehicles with an internal combustion engine 1 by means of an engine coolant pump 7 circulated coolant is cooled, with a self-sufficient thermostatic valve 6 , which for controlling the coolant temperature, the coolant flow rate through the internal combustion engine 1 and the vehicle radiator branch 6a governs, with a bypass branch 6b which additionally varies the coolant flow rate through the internal combustion engine as a function of its cooling requirement, a heating branch 4a and a vent branch 9a , In particular, method for operating internal combustion engines with a conventional Dehnstoff thermostat, characterized in that the vent circuit 9a his water downstream of an additional valve 6bv removes, which varies the coolant flow in the bypass branch and in particular of the electronic engine control 20 is controlled, and that the vent circuit feeds its cooling water at a point upstream of the engine coolant pump into the cooling system, which in each position of the self-sufficient thermostatic valve 6 to the engine coolant pump is open. Apparatus according to claim 23, characterized in that the additional valve 6bv in the bypass line 6b in front of a double-acting self-sufficient thermostatic valve 6 is arranged, in which a radiator-side valve disc the radiator branch 6a upon reaching the control target temperature gradually opens and at the same time a bypass-side valve disc gradually closes the bypass branch. Apparatus according to claim 23, characterized in that the additional valve 6bv in the bypass line 6b a single-acting self-sufficient thermostatic valve 6 is arranged, in which a radiator-side valve disc the radiator branch 6a gradually opens upon reaching the control target temperature and not at the same time a bypass-side valve disc gradually closes the bypass branch. Device according to one of claims 23-25, characterized in that the coolant flow through the bypass branch 6b with closed thermostatic valve 6 and fully open auxiliary valve 6bv is more than 80% of the gas office coolant flow rate through the internal combustion engine. Electrically actuated additional valve, in particular additional valve 6bv for the realization of the methods and cooling devices according to one of claims 1-26, characterized in that an expansion element 6BS when a maximum permitted coolant temperature increase is exceeded above the rated temperature of the radiator thermostat 6 In addition, the electrical control overrides autonomously and the flow path 67 . 68 opens for the bypass branch. Electrically actuated additional valve, in particular additional valve 6bv for the realization of the methods and cooling devices according to one of claims 1-26, characterized in that one with the coolant pressure 69 acted upon actuator 6BX when a maximum permitted coolant pressure is exceeded, the electrical control is self-sufficient oversteers and the flow path 67 . 68 opens for the bypass branch. Self-sufficient additional valve for cooling systems of internal combustion engines, in particular additional valve 6bv for the realization of one of the methods or one of the cooling devices according to any one of claims 1-26, characterized in that one with the coolant pressure 69 acted upon actuator when a maximum permitted absolute coolant pressure exceeds the flow path 67 . 68 through the valve opens and in particular that the valve has a bypass branch 6b opens, which is parallel to the vehicle radiator branch 6a is arranged. Self-sufficient additional valve for cooling systems of internal combustion engines, in particular additional valve 6bv for the realization of one of the methods or one of the cooling devices according to one of claims 1-26, that one with the coolant pressure 69 acted upon actuator when a maximum permitted coolant relative pressure relative to the atmospheric pressure exceeds the flow path 67 . 68 through the valve opens and in particular that the valve has a bypass branch 6b opens, which is parallel to the vehicle radiator branch 6a is arranged. Self-sufficient additional valve according to one of claims 29-30, characterized in that a rotary valve is used as additional valve come on, over an external pressure box is driven and in particular that the coolant pressure when exceeded a setpoint the valve against the atmospheric back pressure plus one Preload force opens. Self-sufficient additional valve according to one of claims 29-32, characterized characterized in that the additional valve is a series-tested Kühlwasserventilbauart with vacuum actuator, in which the original vacuum connection of the Pressure cell instead of the vacuum, the coolant pressure connected becomes. Self-sufficient additional valve 6bv according to any one of claims 28-31, characterized in that the coolant control pressure for the pressure box on the cooling water inlet pipe 67 the additional valve is removed. Method according to one of claims 1-22, in particular using devices according to one of claims 23-33, characterized in that the coolant flow in the heating branch 4a throttled or switched off in operating situations with very high cooling demand. Method and device for operating a cooling and heating circuit for motor vehicles with internal combustion engines 1 with coolant-loaded thermostatic valve 6 for controlling the cooling capacity, in particular the method according to any one of claims 1-22 and in particular using apparatus according to any one of claims 23-34, characterized in that a coolant pressure-operated first valve 6bv upon exceeding an upper limit value for the coolant absolute pressure or the coolant relative pressure relative to a pressure outside the cooling system, a control coolant flow through the coolant-temperature-actuated thermostatic valve 6 releases, so that this heat dissipation through the vehicle radiator 8th to temperature values close to the thermostatic temperature. A method according to claim 35, characterized in that the control current at least in phases with very high cooling potential of the vehicle radiator 8th and high cooling requirement of the internal combustion engine 1 is at least as large or so along the temperature-sensitive area of the thermostatic valve 6 is guided or so mixed with the cold coolant of the vehicle radiator that is in the internal combustion engine in conjunction with not by the thermostat 6 Guided coolant branches sets an approximately homogeneous coolant temperature, so that in particular less than 10 K coolant temperature difference between inlet and outlet result in the internal combustion engine. Method according to one of claims 35-36, characterized in that the thermostatic valve 6 by the flow of an internal expansion element, the temperature control interactively takes over in interaction with the available cooling capacity, as long as the coolant pressure-actuated first valve 6bv the control current through the thermostatic valve 6 has activated. Method according to one of claims 35-37, characterized in that the coolant pressure-actuated first valve 6bv is actuated by an acted upon directly by the coolant pressure actuator and thereby causes the control current through the thermostatic valve. Method according to one of claims 35-37, characterized in that the coolant pressure-actuated first valve 6bv is actuated by an actuator acted upon indirectly by the coolant pressure and thereby brings about the control current through the thermostatic valve, wherein the indirect coolant pressure actuation by means of a pressure sensor takes place via an evaluation unit, in particular the engine control 20 , actuates the actuator of the coolant pressure-actuated first valve.