DE10362350B3 - Method and device for needs-based cooling of internal combustion engines during warm-up - Google Patents

Abstract

Method for operating a cooling and heating circuit for motor vehicles with an internal combustion engine (1) cooled by coolant with a vehicle radiator (8), a heating heat exchanger (4), coolant lines (4a, 6a) for conveying a liquid coolant in a radiator circuit from the internal combustion engine (1 ) to the vehicle radiator (8) and back to the internal combustion engine (1) and in a heating circuit from the internal combustion engine (1) to the heating heat exchanger (4) and back to the internal combustion engine (1), an air-side temperature control (5) of the air conveyed into the cabin, a Thermostatic valve (6), which regulates the coolant throughput through the internal combustion engine (1) and the vehicle radiator (8) to control the coolant temperature, an electronic engine control (20) and a flow-limiting means (2, 15, 2 + 70) in the Heating circuit, which the coolant throughput through the internal combustion engine (1) in Ab depending on their cooling requirement also varies, characterized in that the coolant throughput through the heating system heat exchanger (4) and / or other coolant branches through which the thermostat valve (6) flows is so severely limited that in a warm-up with the heating switched off during the warm-up, no coolant at all or a very low low coolant flow is set through the internal combustion engine (1) and that the cooling and heating circuit has a bypass circuit with a bypass branch (6b) through which the thermostat valve (6) is closed, which bypasses the vehicle radiator (8) and to which an additional valve (6bv) is assigned, for additional Influencing the coolant flow through the internal combustion engine (1).

Description

The invention relates to a method and a device for operating a cooling and heating circuit for motor vehicles with an internal combustion engine cooled by coolant, with an autarkic thermostatic valve 6th , which controls the coolant temperature to control the coolant throughput through the internal combustion engine 1 and the vehicle radiator 8th regulates and a bypass branch that can be influenced by the electronic engine control 6b with additional valve 6bv, which additionally varies the coolant throughput through the internal combustion engine depending on its cooling requirements. In particular, the method is suitable for operating internal combustion engines with conventional expansion material thermostats.

It is known to use thermal management measures to reduce fuel consumption in modern cars. Rapid heating of the coolant and engine oil and thus also the engine component temperatures as well as raising the thermostat opening temperature under partial load are effective means of achieving fuel consumption improvements of 5% and more in the ECE cycle. Future strategies for achieving the full fuel-saving potential by means of such measures include in particular the possibility of freely selecting the opening time of the thermostat by means of the engine control and of varying the coolant throughput through the engine over a wide range during warm-up. Various solutions are available for this, from the magnetic clutch to switch off the coolant pump of the engine to the pump-internal short-circuit valves to the fully variable electronic water pump as a replacement for the belt-driven cooling water pump.

So reveals the DE 197 36 133 A1 a cooling and heating circuit in which a regulated heating circuit pump works against a check valve that only opens from a certain pressure difference, so that the coolant flow in the heating circuit can be interrupted while the coolant pump is running by deactivating the heating circuit pump.

The DE 40 32 701 A1 proposes providing partially separate engine block and cylinder head circuits with separate coolant pumps, the cylinder head circuit having a heat accumulator. When starting the engine from cold, with the engine block circuit largely deactivated by a switching pump, the cylinder circuit is kept in constant circulation until the operating temperature is reached. A heating heat exchanger with air-side air-side regulation of the flow of air through the heat exchanger can be provided in the cylinder circuit.

All known solutions for regulating the coolant throughput through the engine have in common that considerable costs are incurred for the necessary additional components. In addition to the measures for regulating the flow through the engine, most of the known optimization strategies provide in particular for the replacement of the thermostat commonly used today with regulation of the cooler flow by means of an expansion element by a valve that can be freely controlled by the engine control. In order to fully exploit the potential, relatively complex valves in particular are provided in which the flow through the cooler is specified by the engine control and is sensitively adjusted via a stepper motor. Different rotary positions of the multi-way valve then set e.g. preferred positions for optimal hot cooling, maximum cooling effect or maximum cabin heating output. The costs for such a valve to switch multiple inflows and outflows, e.g. for the cooler, bypass and heating circuits, or to vary them continuously, are not insignificant. In addition, there is a further additional effort if a sufficient fail-safe behavior is to be implemented for all possible summer and winter operating conditions.

The costs are therefore already considerable, even if, without using the full fuel-saving potential, provision is made for an additional measure to vary the coolant pump speed or the coolant pump delivery rate at the same time as the valve is introduced.

Not least against the background of costs and operational safety, a much simpler system for hot cooling has prevailed on the market, in which an expansion thermostat with an electrically heatable expansion element enables optional operation at two different coolant temperatures. A thermostat with an expansion element is used, which inevitably begins to open from 100 ° C, for example; when the heating element is energized, this opening time is then shifted to 80 ° C by means of the electrical heat supply to the expansion element. The fuel consumption advantages are not fully exploited here, partly because the effectiveness of the system is limited to driving situations with coolant temperatures above approx. 80 ° C, but the additional costs are also significantly lower. In addition, any discussion regarding the robustness of the system and its fail-safe characteristics as well as the The question of the availability of components ready for series production is largely irrelevant in view of the already existing series experience with this type of electrically heated thermostats.

Nevertheless, the system suppliers for vehicle cooling systems are working on the variants described above to fully exploit the fuel-saving potential of thermal management measures. However, the success of these new approaches is, on the one hand, largely linked to the development of emissions regulations and fuel consumption, and on the other hand, is also very much linked to the provision of much cheaper hardware than was previously available. Conversely, the failure to start large-scale production makes falling hardware prices for the electronic multi-way valve as a thermostat replacement and possibly the switchable or controllable cooling water pump more difficult.

In contrast, the object of the present invention is to create a particularly cost-effective and yet operationally reliable cooling and heating system in which a fuel-saving potential can be used by thermal management measures.

The values of the electrically heated thermostats, such as those currently installed in vehicles of the BMW and Ford brands, i.e. in particular the setting of the coolant temperature by means of the engine control to values between, are currently to be regarded as particularly desirable or to be surpassed for the temperatures and costs 80-85 ° C with high load and 100-115 ° C with partial load.

This object is achieved with the method according to claim 1 or 2 and by a cooling and heating circuit designed according to claim 10.

In the year-round operation, fuel consumption savings are possible that even significantly more expensive systems with complex multi-way valves and variable coolant pumps cannot achieve. Even in the statutory emission tests at 25 ° C (ECE, MVEURO, FTP), the fuel saving potential with cold starts as well as with hot repeat tests is at the level of the much more expensive systems.

As will be shown later, a very important advantage for the overall system is that, in conjunction with a high-performance cabin heat exchanger, it delivers the fuel consumption benefits not only in the emissions test at + 25 ° C and with the cabin heating switched off, but also when the cabin heating is switched on.

First, however, the more general case will be described with a particular focus on the statutory emissions test.

This is where the means play a role 2 , 4th , 15th and 9a an essential role that the coolant flow through the heating heat exchanger circuit 4a , the ventilation circuit 9a and / or others even when the thermostat is closed 6th Strongly limit the flow of coolant branches. In the ventilation circuit 9a A minimization of the line cross-section or the insertion of a throttle orifice is sufficient here, better with regard to the effect during warm-up and the minimization of the venting risk is of course a switchable valve. In the heating circuit 4a is the flow limitation by means of the valve 15th or / and by dimensioning the pressure loss in the heating system heat exchanger 4th and in the coolant lines in conjunction with the optional electric pump 2 accomplished. With the thermostat 6th If a largely conventional design is used with an expansion element as an actuator, which begins to open at 82 ° C., for example, electrical heating of the expansion element is not necessary.

For the exhaust test at + 25 ° C, a very low coolant flow is set during the warm-up by means of the bypass valve 6bv, the coolant throughput in the heating heat exchanger and ventilation circuit being as low as possible, preferably even zero. This increases the temperature of the combustion chamber wall, the temperature of the cylinder liner and also of the water and oil. The advantages achieved hereby are lower engine friction and improved combustion.

At the same time, the drive power of the motor pump is reduced 7th , since the strong reduction in the delivery rate overcompensates for the limited increase in delivery pressure caused by the pump characteristics.

In the case of gasoline engines, there is also a slight partial throttling of the engine due to the higher intake air temperature. In contrast to the known electrically heated thermostat, these advantages are effective right from the start and not only when the conventional thermostat opening temperature of 82 ° C, for example, is reached.

If the coolant reaches the thermostat opening temperature of 82 ° C, the thermostat begins to open and keeps the engine inlet temperature at values close to 82 ° C, while the engine outlet temperature, in view of the still very low coolant flow rate of 2 l / min, for example, more and more towards the maximum permissible temperature of, for example, 115 ° C strives. Sections of the combustion chamber walls are already so warm that nucleate boiling begins locally in the water jacket. At 97 ° C, the mean coolant temperature is thus well above the thermostat opening temperature of 82 ° C. Compared to known systems with electrically heated thermostats, due to the significantly lower coolant throughput to increase the mean coolant temperature, there is also a significantly lower heat transfer coefficient on the cooling water side, so that the effective component temperature and in particular the temperature of the cylinder liner are sometimes even slightly higher and therefore more efficient in terms of friction . In other words, with the additional costs for a simple two-way valve 6bv, which is also very small in particular, since it only has to manage the bypass volume flow and not the entire cooler flow, not only the effect of the electrically heated thermostat can be achieved, but even the effect of the complex multi-way valve.

As the critical component or coolant outlet temperature approaches, the bypass volume flow is gradually increased, if necessary. The thermostat outlet temperature initially rises relatively little, since relatively cold coolant from the radiator mixes with hot coolant from the engine outlet. However, the increase in the coolant throughput through the engine leads directly to the increase in the heat transfer coefficient on the cooling water side, which is desired in this operating phase.

If there is a high cooling requirement, the bypass is initially completely open, i.e. the cooling system is identical to a conventional cooling system with 82 ° C thermostats and is correspondingly safe.

A potential failure of the bypass valve 6bv does not lead to serious problems, neither in the open nor in the closed state, if the engine control removes the suppression or reduction of the flow in the other branches of the engine-internal cooling circuit at excessive temperatures. To further increase the fail-safe properties, however, it is particularly advantageous if an additional thermostat or a superimposed expansion element overrides the electronic control of the bypass valve and opens the bypass branch when the coolant temperature is too high.

Decisive for the fact that with the procedure according to the invention a fuel consumption advantage can also be realized in the upper temperature range, which e.g. corresponds to the consumption advantage of the electrically heated thermostat when the engine is at operating temperature, is the minimization of the total coolant throughput through the engine in the direction of the maximum permissible component and coolant temperatures.

In the case of the cooling and heating systems for cars that can be found on the market today, this generally fails because the bypass branch is parallel 6b Several further branches are arranged, through which the flow occurs when the bypass is open as well as when the bypass is closed, and also when the vehicle radiator is open and closed. The only examples are the oil cooler and the cabin heater with air-side temperature control. Opening and closing the bypass valve here, without the changes according to the invention, only causes a relatively small bandwidth for the variation of the coolant mass flow through the engine in the range of, for example, 15 l / min to 75 l / min. This also causes a variation in the heat transfer coefficient and thus a slight increase in component temperatures, but much less than is aimed for during warm-up: there, volume flows of 0-2 l / min are more of interest. Last but not least, this problem has paved the way for the development in the direction of the electronic multi-way valve described at the beginning, in which not only the closing of the cooler circuit as required but also the bypass and the heating and possibly also the ventilation circuit is handled by a central multi-way valve becomes.

In contrast, the procedure according to the invention suggests, in particular for the heating and other parallel branches of the inner cooling circuit, not to use a complex multi-way valve, but to provide a simple two-way valve 6bv in the bypass branch and, if necessary, means external to the engine that allow the total coolant throughput through the engine by actuating the Adjust bypass valve 6bv down to very small values. This can be additional active actuators such as valves 15th but preferably inexpensive passive actuators such as high-performance heat exchangers 4th with increased pressure loss, which are specially dimensioned for low coolant throughputs. The use of the counter-flow design with minimized coolant line cross-sections, if necessary with a small additional electrical pump, is particularly suitable for cabin heating 2 .

The advantages of the low coolant throughput in the warm-up phase can be realized just as well with the system according to the invention as with the complex multi-way valve, combined with significantly lower costs for the overall system. Of particular interest here is the possibility already described to also deliver the advantages of the function “Increase of the thermostat opening temperature in the partial load” without any additional costs. This would not be possible without the procedure according to the invention for providing a control range for the coolant flow through the engine down to values that are too small.

A numerical example should make this clear again for the case of low waste heat, ie low coolant throughput through the vehicle radiator and radiator outlet temperature close to the ambient temperature of 25 ° C. For example, if the amount of heat pumped into the cooling water is 4 kW, as is the case when driving slowly in city traffic, the following picture arises at a thermostat opening temperature of 82 ° C: At 2 l / min by the engine: $$\begin{array}{l}{\text{DT}}_{\text{Water\_engine}}=33\text{K}\to {\text{T}}_{\text{Motor\_output}}=82°\text{C.}+33\text{K}=115°\text{C.}\hfill \\ \to {\text{T}}_{\text{Water\_engine}\text{, Mitter}}=82°\text{C.}+\text{33}/\text{2K}=98.5°\text{C.}\hfill \end{array}$$

At 15 l / min through the engine: $$\begin{array}{l}{\text{DT}}_{\text{Water\_engine}}=4.4\text{K}\to {\text{T}}_{\text{Motor\_output}}=82°\text{C.}+4.4\text{K}=86.4°\text{C.}\hfill \\ \to {\text{T}}_{\text{Water\_engine}\text{, Mitter}}=82°\text{C.}+4.4/\text{2K}=84.2°\text{C.}\hfill \end{array}$$

This makes it clear how important the inventive minimization of the coolant flows in the cabin heat exchanger or oil cooler is: A control range of the total coolant mass flow through the engine by means of the bypass branch 6b from 15-75 l / min is not expedient against this background. This applies if the series-typical thermostat with an opening temperature of 82 ° C is retained from the time the thermostat opening temperature is reached and especially in the early phase of warm-up.

In addition to the drop in average coolant temperature from 98.5 ° C to 84.2 ° C shown as an example, at a coolant throughput of 15 l / min, a further disadvantage with regard to the component temperature increase in the partial load is the higher heat transfer coefficient and an - even if only slightly - increased Drive power of the motor pump 7th .

It is basically not new to work with coolant flow rates below 15 l / min at partial load until the thermostat opening temperature is reached in order to save fuel. What is new, however, is to accomplish this with a single two-way valve 6bv and what is new is to achieve the same or even better fuel consumption advantages above the usual thermostat opening temperature of, for example, 82 ° C than with an electrically heated thermostat with the option of adjusting the thermostat opening temperature of, for example 82 ° C to 102 ° C.

In addition, a particularly preferred variant using the cabin heat exchanger and / or the oil cooler as a heat sink ensures that the vehicle cooler 8th is really only switched on when this is unavoidable. The procedure according to the invention is therefore of particular importance with a view to year-round operation, where there is generally a starting temperature well below 25 ° C and thus the oil often only reaches the coolant temperature after a very long period of driving and where heating power is also generally taken. Without the inventive minimization of the total cooling water mass flow through the engine to a few l / min, for example, a cooling water mass flow of 15 l / min in the heating circuit would inevitably lead to the thermostat opening at a little above 82 ° C.

The procedure according to the invention thus makes it possible to dispense with the electrically heated thermostat or even the freely controllable multi-way valve and still largely exploit the potentials in terms of fuel consumption and emissions that can be achieved from the targeted increase in the component temperature during warming up and warming up. In addition, there are not negligible advantages from the savings in pump drive power in all operating situations with reduced bypass volume flow and fully or partially closed thermostats. The increased pressure losses due to the throttling of the coolant throughput through the engine are overcompensated by the lower coolant throughput.

The electronic multi-way valve can in principle also deliver this, but without the inventive adaptation of the heating circuit, however, with considerable restrictions with regard to the utilization of potential in year-round operation.

The electronic thermostat cannot provide such advantages with regard to the pump drive power, which are particularly effective from the start on every journey.

Against this background, the cost advantages of the procedure according to the invention are considerable.

1 shows a particularly advantageous embodiment of an engine and vehicle cooling system for carrying out the method according to the invention, taking into account, by way of example, measurement and control lines that are important for controlling the coolant throughput according to the method 20a-20d of the engine control unit 20th .

The coolant is according to 1 through the engine cooling water pump 7th by the engine 1 promoted. The coolant flows from the engine outlet in a first circuit 9a to the water tank 9 and then over the thermostat 6th back to the engine 1 . This branch is used for ventilation and degassing and, in order to minimize heat losses during warm-up and for reliable degassing, in particular contains a throttle point (not shown) for reducing the coolant throughput to values close to zero at low engine speeds. Alternatively, instead of the throttle point, a two-way valve can carry out even more precise control or temporary shutdown during warm-up.

A second branch of the cooling system goes over the pipe 6a and the vehicle radiator 8th to the thermostat 6th or by means of the motor control cable 20d switchable bypass branch 6b with switching valve 6bv directly to the thermostat 6th . The thermostat 6th can be a double-acting thermostat that automatically closes the bypass when the cooler circuit is fully open, or a single-acting thermostat that is always within the thermostat for the bypass branch 6b is open. The line of the branch 6b can optionally also be used for the return of the heating circuit with the single-acting thermostat 4a be directed. The thermostat opens at a certain operating temperature 6th the radiator branch 6a more and more and keeps the coolant inlet temperature to the engine almost constant. If the radiator branch is largely open and there is a high cooling requirement, it may be advantageous, depending on the engine and radiator variant, if the bypass valve 6bv is closed; in the case of a double-acting thermostat, the bypass branch is closed 6b inside the thermostat 6th with the thermostat fully open 6th necessarily closed, detached from the selected position of the el. bypass valve 6bv.

Next to the branches 6a , 6b , and 9a the branch is used to cool the engine or vent the cooling system 4a the heating of the vehicle cabin. The coolant is supplied by the electronic auxiliary pump 2 via one from the engine control 20th controllable flow control valve 15th to the cabin heat exchanger 4th and then back to the thermostat 6th promoted.

Optionally, it is also sufficient to regulate the flow of the heating by means of a flow limiting valve 15th and / or by means of increased pressure losses in the heating branch 4a to undertake.

The design of the system is even simpler and particularly efficient with regard to rapid cabin heating 1 if a special high-performance cabin heat exchanger 4th and a gear pump 2 is used with an adjustable volume flow of 0-2 l / min. A sufficiently small and sufficiently precisely meterable volume flow is then problem-free without the valve 15th realizable.

In heating mode, the coolant volume flow is deliberately set to low values of, for example, only 2 l / min, at least when the engine is cold or when there is a heat deficit, by including the line cross-sections in the heating branch 4a instead of the usual 16-22 mm inner diameter only have 4-6 mm inner diameter, and the bypass branch 6b and the radiator branch 6a are closed in the event of a heating deficit. The cabin heat exchanger is also designed for a relatively high pressure loss in order to achieve high flow rates of the coolant and good heat transfer in the individual heat transfer tubes. In contrast to the cross-flow heat exchanger design typical of cars, the counter-flow design is preferably used, which usually has a greater water-side pressure loss anyway.

By installing the additional electrical pump 2 which, in contrast to the centrifugal pumps commonly used in vehicle cooling, is particularly advantageously designed as a diaphragm, piston or gear pump, In connection with the design according to the invention of the cabin heat exchanger and the coolant lines for a very low coolant volume flow and high pressure losses, the result in the heating circuit is a coolant throughput that is largely independent of the engine speed. The fact that for the cooling system of today's internal combustion engines usually a pressure and power requirement of the engine-side coolant pump that is as moderate as possible is involved in this fact 7th is strived for. The pressure differences in the other branches are therefore small compared to the values in the specific embodiment of the variant according to the invention. When using, for example, a gear pump as an additional pump 2 Therefore, the flow through the cabin heat exchanger is in a first approximation due to the electrical power of the gear pump 2 determined and not by the motor pump 7th . Compared to today's cooling and heating systems, an overall system designed in this way leads to a dramatic improvement in the cabin heating capacity even without additional measures to artificially increase the waste heat from the engine. The physical mechanisms of action used here with regard to the effective heat-active masses have already been described in detail.

In addition to the advantages in terms of heating effect and faster engine warming, which in addition to improved comfort, especially in winter, lead to considerable fuel savings, the system in particular offers according to 1 the possibility of setting the coolant volume flow in the heating circuit and thus the total volume flow through the engine so low that there is a corresponding heat extraction at the cabin heat exchanger 4th and closed bypass branch 6b not to open the thermostat 6th comes.

With low engine load and very high heat extraction for the cabin, with today's passenger car diesel engines, even with the usual coolant flows through the cabin heat exchanger, it is already quite often the case that the coolant temperature is well below the thermostat opening temperature. However, in view of the comparatively high coolant flows through the engine or the cabin heat exchanger, this state occurs here because the waste heat is hardly sufficient for the heating anyway and the coolant temperature at the engine outlet is already below the thermostat opening temperature and not because of a set value specifically to very low values Coolant flow through the engine and the associated heat sink (s).

With the system according to the invention, on the other hand, the situation described above, with hot coolant at the engine outlet and still closed thermostat, is deliberately brought about in a targeted manner and also with increased waste heat supply or low heat extraction for the cabin by the engine control via the bypass valve 6bv through the total coolant throughput Motor limited.

In the event of load changes and increased cooling requirements, the motor control opens the bypass branch 6b and thus at the same time improves the cooling effect via the better heat transfer coefficient at higher flow rates. The maximum coolant temperature falls, the mean coolant temperature increases slightly and the mean component temperature falls. At the same time, the high coolant inflow from the bypass branch with relatively warm coolant dominates over the initially still relatively low coolant inflow from all other branches and, if necessary, leads to the thermostat opening very quickly. The time constant of the engine cooling effect is significantly better than with the electrically heated thermostat, since the bypass valve opens without a time delay and performs a first internal engine cooling immediately when the load increase is initiated. The lower opening temperature of 82 ° C - relative to, for example, 102 ° C for the electrically heated thermostat - increases the safety reserves and represents a more than sufficient temperature difference between the expansion element and the coolant to be in contact with the comparatively warm coolant at the time the bypass is opened ensure the necessary heat supply for a quick opening of the thermostat at the motor outlet.

With the thermostat and bypass open, the result is a largely conventional cooling system with the operating behavior known from millions of series applications.

When operated without heating, the cooler takes on the function of the heating heat exchanger as a heat sink. Since the coolant flow is usually very low here too when driving at part load, the effect is exactly the same as described above.

In contrast to known solutions with multi-way valves, in which a stepper motor generally moves to the various rotary positions of a rotary slide valve, in particular for hot cooling, maximum cooling effect and maximum heating effect, the design according to the invention has the particular advantage that the heating, the bypass and, in some cases, also the opening of the Thermostats can be controlled decoupled from each other. This not only increases the room for maneuver to maximize the benefits of the Thermal management measures, in particular, make the control for safe summer and winter operation considerably easier.

A particularly effective control results in this context, in particular with a low basic coolant throughput through the cabin heat exchanger of, for example, 0-2 l / min: Regardless of whether it is summer or winter operation or high, little or no heat extraction at the cabin heat exchanger, the wide range of variations in the coolant throughput through the Bypass of 0-50 l / min, for example, and the freely selectable and quickly effective controllability of the bypass valve 6bv makes a distinction between summer and winter operation largely unnecessary with regard to the safety and efficiency of the cooling, as long as a suitable sensor reliably records the engine operating temperature.

Conventional systems, which work with a high coolant mass flow through the heating heat exchanger in winter - today standard values are around 15 l / min at speeds of the drive motor of 1500 1 / min - require, among other things, a switch-off device for the heating circuit in summer or in order to implement this range of variation in the engine-internal coolant flow rate with moderate heating requirements.

Even with a simple on / off switching function of the electric pump 2 has the system according to the invention according to 1 here considerably more degrees of freedom. In particular, the potential for saving drive power for the engine-side coolant pump can still be largely exploited when heat is extracted for the cabin.

Simply switching off the electric pump when the engine is cold and at the same time closing the bypass valve 6bv in the first few minutes of warm-up also provides additional fuel savings in addition to increasing the engine component temperatures by saving the pump drive power of the engine pump when operating without heating or in the statutory emissions test 7th .

The practical implementation of this shutdown is indeed feasible with the rotary slide valve already described, but it is particularly dependent on compromises that optionally enable maximum winter heating, but then do not allow optimal fuel savings or vice versa.

A publication by a well-known system supplier for heating and cooling systems at the "Thermal Management of Motor Vehicles" conference in September 2002 describes in this context the still common control strategy of such a multi-way valve with regard to heating and praises the important advantage that the system enables to achieve an improved cabin heating effect in partial load and idling in the event of a heating power deficit by means of a very high coolant mass flow through the heating heat exchanger.

In particular, with rotary valves of this type, the engine-side bypass is generally closed within the valve, so that the coolant mass flow through the heating heat exchanger increases, for example, to values of 15 l / min or more when idling, combined with an improvement in the efficiency of the cabin heat exchanger itself Operating situations with both cold and warm engines, the possibility of raising the engine component temperature and thus saving fuel by means of the lowest possible coolant mass flow of, for example, 2 l / min through the engine and the same heating effect, is blocked. The arrangement according to 1 with high-performance heat exchanger 4th , especially with a flow range of 0-2 l / min, does not change this option. The freely controllable bypass valve 6bv not only enables largely the same engine operating states as the variant with a high coolant throughput through the cabin heat exchanger, but also extends the range of variation to very small and also to very large coolant throughputs through the engine, without loss of heating comfort. Corresponding fuel savings are the result if this potential is fully exploited.

The system according to the invention is particularly advantageous even without the additional consideration of the fact that in future heating systems, especially if there is a heating power deficit, special heating heat exchangers and the lowest possible coolant flow rates through the heating heat exchanger will be used. In particular, the free choice of the bypass throughput in the branch 6b and the additional option of freely selecting the heating heat exchanger throughput also opens up the possibility of controlling the cabin temperature on the water side at no cost. The advantages with regard to the package in the heater are considerable with cabin temperature control on the water side. Likewise, the options for switching off the coolant throughput through the heating heat exchanger with air-side cabin temperature control are very advantageous.

In this context, it is even more important that, in contrast to today's control strategies, the coolant throughput through the cabin heat exchanger will not only be significantly lower in the future than is usual today in order to minimize the effective heat-active mass in the heating circuit and that, in some operating situations, the coolant throughput through the cabin heat exchanger is not increased but reduced to improve the heating effect. The increase in the flow temperature of the coolant heat exchanger by means of the flow reduction through the engine and / or the other heat sources external to the engine in the heating system heat exchanger flow overcompensates the sensitivity of the heating system to the coolant throughput in these systems. Last but not least, the implementation of this additional measure, i.e. increasing the cabin heating effect at least in some operating points by reducing the coolant throughput through the heating heat exchanger instead of the usual increase, requires additional effort in terms of design, the control strategy and the vehicle-specific coordination of the rotary slide valve, which is in competition with the system according to the invention . In particular, the interaction of the 3 branches of heating, bypass and cooler using only one stepper motor for the angle of rotation makes considerable demands on the positioning accuracy and control quality even without this requirement with regard to the heating operation.
In addition, the effort and the risk of errors for coordinating the overall system for maximum fuel savings increases, since there are very different ranges of variation for the coolant flow through the engine for summer and winter operation.

In addition to influencing the heating, preventing or limiting the coolant flow through the cooler is advantageous for both gasoline and diesel engines in order to keep the thermal energy in the system at partial load and to enable increased component temperatures. The system according to the invention basically offers at least the same fuel-saving potential as the much more expensive solution with the electronic multi-way or rotary slide valve as a thermostat replacement and a significantly better fuel-saving potential than the electrically heated thermostat alone. The advantages of the counter-flow cabin heat exchanger and the small coolant line cross-sections can also be used with the multi-way valve, but the cost-benefit balance is then worse than with the two-way valve in the bypass branch 6b .

• • die winterliche Heizleistung dramatisch besser wird und die Kosten und der Kraftstoffmehrverbrauch für potenzielle el. Zuheizungen entfallen,
• • das Package der Schlauchleitungen einfacher wird und angesichts der geringen Biegeradien die Kühlmittelleitungen der Heizung als Meterware von der Rolle bezogen werden können anstelle der Verwendung motor- und fahrzeugspezifischer Maßanfertigungen,
• • die regelbare Pumpe, z.B. als Zahnradpumpe oder als Impellerpumpe mit federbelastetem Ventil ausgebildet, im gesetzlichen Abgastest und bei sommerlichem AC-Betrieb ähnlich wirkt wie ein Abschaltventil im Heizkreislauf,
• • die Kühlmittelpumpe des Motors kleiner gewählt werden kann, da keine künstliche Drosselung am Thermostaten erforderlich ist, um die Kühlmitteldurchflusskriterien des Heizungswärmetauschers bei geöffnetem und geschlossenem Thermostaten zu erfüllen (Hieran ist u.a. zusätzlich eine leicht erhöhte Maximalleistung des Motors und ein verbesserter Kraftstoffverbrauch in allen Drehzahlpunkten mit erhöhter Motordrehzahl gekoppelt sowie eine reduzierte Kavitationsgefahr),
• • potenzielle Hot Soak Probleme mit der kleinen el. Zusatzpumpe gehandhabt werden können und somit näher an die physikalischen Grenzen gegangen werden kann,
• • ein zusätzlicher Kundennutzen durch Restwärmenutzung bei Fahrzeugstillstand kostenneutral und mit geringem Strombedarf realisiert werden kann bzw. bei Start/Stop-Automatik des Fahrzeugantriebs keine Mehrkosten anfallen,
• • der Kraftstoffverbrauchsvorteil bereits in der frühen Warmlaufphase beginnt,
• • der Kraftstoffverbrauchsvorteil mit und ohne Kabinenbeheizung wirksam ist, sowie
• • neben der Kraftstoffeinsparung aus der Erhöhung der Motorbauteiltemperatur am kalten wie am warmen Motor auch in fast allen Fahrsituationen eine Kraftstoffeinsparung über eine Reduktion der Pumpenantriebsleistung erfolgt, da der Thermostat nur sehr selten weit geöffnet ist und/oder der Motor bei Volllast betrieben wird.

A cost-benefit balance also shows that the use of the method according to the invention in conjunction with a small electric pump, in particular a controllable pump with a control range of 0-2l / min and a power consumption of less than 2A, and a counterflow heat exchanger with Coolant lines with an inner diameter of 6 mm and below are particularly advantageous because, among other things

• • The winter heating performance is dramatically better and the costs and additional fuel consumption for potential electrical additional heating are eliminated,
• • The hose line package becomes simpler and, given the small bending radii, the coolant lines for the heater can be purchased by the meter from the roll instead of using engine and vehicle-specific custom-made products,
• • The controllable pump, for example designed as a gear pump or as an impeller pump with a spring-loaded valve, acts similarly to a shut-off valve in the heating circuit in the statutory exhaust gas test and in summer AC operation,
• • The engine coolant pump can be selected to be smaller, as no artificial throttling is required on the thermostat to meet the coolant flow criteria of the heating system heat exchanger with the thermostat open and closed (this also includes a slightly increased maximum engine output and improved fuel consumption at all speed points coupled with increased engine speed and a reduced risk of cavitation),
• • Potential hot soak problems can be handled with the small additional electrical pump and can therefore be approached closer to the physical limits,
• • An additional customer benefit through the use of residual heat when the vehicle is stationary can be realized cost-neutrally and with a low power requirement or there are no additional costs with automatic start / stop of the vehicle drive,
• • the fuel consumption advantage already begins in the early warm-up phase,
• • the fuel consumption advantage is effective with and without cabin heating, as well
• • In addition to fuel savings from increasing the engine component temperature on both cold and warm engines, fuel savings are also achieved in almost all driving situations by reducing the pump drive power, as the thermostat is only very rarely open and / or the engine is operated at full load.

A comparison of the system costs with a system with a multi-way valve with or without a controllable engine coolant pump, which is approximately comparable in terms of emissions and fuel savings, is clearly in favor of the system according to the invention 1-3 out. This applies to vehicles with gasoline engines and even more so to diesel vehicles, in which the elimination of the electrical auxiliary heating or even the auxiliary burner represents a very significant additional saving potential.

2 shows in this context a particularly effective application example on a vehicle with a turbo diesel engine. The el. Pump delivers 2 , which is preferably designed as a controllable miniature gear pump with 0-2 l / min, the coolant via the EGR cooler 30th and the heating system heat exchanger 4th . The associated coolant line is here 4a The heat exchanger is characterized by a particularly small inner diameter of approx. 4-6 mm in the area drawn in dashed lines 4th is specially designed for the low volume flow in counterflow design. The package volume in the heater, which was originally filled with an electrical PTC auxiliary heater in the specific application, is also used to maximize the heat exchanger efficiency. In the thermal influence area of the EGR cooler is the bypass valve 6bv, which consists of an active valve 6bf, that is freely controllable by the engine control, and a passive valve or actuator 6bs, that is activated by the heating of the cooling water, which the active valve 6bf if the temperature is too high and / or the delivery pressure is too high at extreme engine speed, it overrides and opens.

In the simplest case, an expansion element with an opening temperature of 105 ° C., for example, presses open the valve disk of a solenoid valve if the coolant temperature is too high. However, a complete thermostatic valve 6bs can also be connected in parallel to the active valve 6bf.

• • eine Teilwirkung die der Heizleistung zu gute kommt und
• • eine Teilwirkung die auf eine Kraftstoffersparnis führt.

With the bypass branch closed 6b the entire coolant flow flows through the cabin heat exchanger 4th , an additional Degas valve 9c stops the flow through the cooling water tank if there is a heat deficit 9 . When heat is extracted at the cabin heat exchanger and the engine load is low, coolant outlet motors are induced in this way at the EGR cooler up to 105 ° C, at the engine inlet these remain at values below 82 ° C. This accelerates the heating of the cabin, since the entire heat-active mass does not have to be heated up. At the same time, the temperatures of the combustion chamber walls and the cylinder liner increase locally, despite the deactivated oil cooler 40 to a certain extent also of the engine oil, combined with a reduction in fuel consumption. In other words, the energy savings due to the lower effective heat-active mass are divided into

• • a partial effect that benefits the heating output and
• • a partial effect that leads to fuel savings.

If the temperature difference across the motor is too great or if the coolant or component temperature is too high, the motor control opens 20th the bypass valve 6bv. In a first step, this is preferably done only partially, so that the oil cooler 40 can be used as a heat sink. This is important for many operating situations, since the oil temperature is well below the coolant temperature for a long time when the load is low when the engine is warming up. In this mode of operation according to the invention, the increased temperature potential of the coolant at the engine outlet provides additional support for heat transfer in the oil cooler.

If the engine load is very high or there is a risk of overheating, the bypass valve 6bv opens completely, and a high coolant mass flow then flows over the oil cooler 40 to the heating return and then to the radiator thermostat 6th . The flow branch 6b preferably has significantly larger hose lines than the pure heating branch 4a to ensure that there is a sufficiently high coolant throughput through the EGR cooler if required 30th and the oil cooler 40 flows. This is important in order to reliably avoid overheating of the EGR cooler and, if necessary, to use the full potential to reduce the engine cooling water pump output at partial load. At the same time, the option of a high throughput is important in order to ensure a high response speed of the thermostat in those phases in which the oil cooler acts as an additional heat sink.

The thermostat 6th In contrast to the original engine cooling system with bypass thermostat, it is no longer a double-acting thermostat, but a single-acting variant, so that there is additional cost savings.

Another variant of integrating the oil cooler 40 shows 3rd . This variant is particularly advantageous in order to achieve a particularly good heating effect: The low cooling water outlet temperatures from the countercurrent heat exchanger 4th extract heat from the engine oil in favor of cabin heating, but to the detriment of fuel consumption.

The components for realizing the cooling and heating system according to the invention can in particular be constructed using hardware that is already available on the market. This is important in order to implement a quick implementation in the vehicle series. The cost advantages arise in particular when the vehicle is used for the first time, i.e. when the component development and production facilities are amortized, costs do not have to be amortized over several vehicle applications.

An essential key for the full implementation of the ideas according to the invention is the - contrary to original doubts on the part of the system suppliers - now experimentally confirmed by rig tests and vehicle tests that heating heat exchangers with the properties according to the invention, in particular with sufficient heating heat exchanger efficiency at very low coolant throughputs down to 2 l / min and less, technically feasible and can be accommodated in the heater of today's and future cars. It is a very special advantage of the method according to the invention that, in the interaction of the individual changes, it is possible to dispense with the electrical PTC auxiliary heating, which is now very frequently found in diesel cars. Although this package room is generally is not required to achieve the necessary cabin heat exchanger efficiency, it nevertheless increases the design leeway for the cost-effective construction of a corresponding heat exchanger with semi-finished products already available on the market, in particular for the application-specific optimal pressure loss in the heating system with or, if necessary, also without an additional electric pump in the heating circuit .

To optimize the system advantages while minimizing the component costs, it is particularly advantageous to use the in 4th to use schematically shown bypass valve.

The electric coolant pump 2 sits here in the case 60 of the bypass valve 6bv with integrated safety thermostat valve, shown here as an example with electronic switching magnet 6bf and expansion material actuator 6bs as a safety thermostat. Here is the contact pressure of the spring 62 between valve guide housing 64 and valve seat 65 chosen so that the expansion material actuator 6bs with its stamp 66 the valve 6bv against this spring 62 when a limit temperature of, for example, 105 ° C is exceeded. This means that by means of the motor control via the control line 63 Any setting made to the bypass valve 6bv is possibly inevitably canceled.

In the in 4th The variant shown, the bypass valve 6bv is closed in the event of a power failure and only opens when the expansion material actuator engages. This has the advantage that the electrical current for the actuator 6bf is required with a relatively low frequency, since the bypass is closed in most driving situations. For motors that have the bypass open more often than it is closed, however, it is advantageous to adapt the design so that the bypass valve is open in the de-energized case. This is easily possible, for example, by repositioning the spring and adjusting the magnet armature. This variant has the particular advantage that, in the event of a cable break, additional protection against overheating is built in; the radiator thermostat then works like a conventional bypass thermostat with an open bypass in the event of overheating.

Regardless of the variant selected, it is advantageous for the reliable function of the expansion material actuator 6bs to arrange it upstream of the valve disk so that it still works well even when the bypass is closed. In addition, it is particularly advantageous to choose the installation position of the bypass valve so that the expansion material actuator still works reliably via the thermosyphon effect even when the heating branch and the bypass branch are closed and opens when the coolant temperatures are too high. Alternatively, a small leakage flow in the bypass branch can be used to ensure the correct function of the expansion material actuator.

In the particularly effective design variant in 4th two relatively large coolant connections for coolant lines with an inside diameter of 20 mm, for example, identify the bypass connection to the engine or EGR cooler outlet 67 as well as the return to the motor 68 . In contrast, for the heating branch, for example, only 6 mm inner diameter is provided, ie the ratio of the flow cross-sections is greater than 10: 1.

This offers particular advantages with regard to the overall component size and the connection of the lines in the vehicle, as well as advantages with regard to the integration of the electronic coolant pump 2 including flow control aids 69 , 70 , 71 in a common housing 60 .

If the flow limitation of the heating is done externally, e.g. with the valve 15th according to 1 , or if the electronic auxiliary pump is not integrated, a larger coolant connection can in principle also be used 72 be used. A much more efficient package and in particular the generally desired minimization of the heat-active mass of the heating circuit make the variant with, for example, 6 mm inside diameter of the heating coolant line instead of the usual 16-22 mm particularly attractive. 6th shows a corresponding design with integrated resources 69 , 70 , 71 for pressure flow control in the heating circuit for external el. additional pump 2 , 7th the corresponding design, even if the means for flow control are arranged externally.

The electronically from the engine control over the line 73 controllable electronic miniature cooling water pump 2 promotes in the design accordingly 4th the cooling water through the spring-loaded valve 70 to the heating connection 72 with preferably less than 6 mm inside diameter. Here is the contact pressure of the spring 69 selected at least high enough that the valve when the electronic miniature pump 2 from the seat 71 lifts, but is not opened by the pressure of the engine cooling water pump. This ensures, among other things, that the heating circuit initially remains switched off in the statutory emissions test, so that this heat-active mass does not delay the warm-up process. If there is a need for cooling, this heat-active mass can be switched on quickly and, for example, when accelerating in the EUDC, it can help avoid the need for the cooler fan temporarily. Further advantages of the free connection and disconnection option of the heating circuit, in particular with regard to the winter heating effect and the operation of the air conditioning system in summer, have already been described.

As a particularly advantageous refinement, it is easily possible here, instead of the pure switching option, to set the coolant flow through the heating heat exchanger precisely, regardless of the engine speed and its thermal operating situation. In the design according to 4th it is sufficient here, the spring force of the spring 69 to choose relatively large and the valve disk relatively small, so that a relatively large delivery pressure of the electronic miniature pump 2 of, for example, 1 bar overpressure is required for opening. The range of variation of the pressure fluctuations imposed by the engine's cooling water pump when the speed changes are generally significantly smaller, so that the delivery rate in the heating circuit is clearly determined by the setting of the electric pump 2 is defined by means of the engine control. In the simplest case, the variation is a switching function, for example between flow zero and 2 l / min, but a performance graduation or regulation of the electronic pump is particularly advantageous 2 , so that there is a step-by-step or stepless setting of the heating flow.

As an alternative to flow control by regulating the pump output and strong throttling, a flow limiting valve can optionally be used, which e.g. limits the flow to 2 l / min when the electrical pump is switched on, regardless of the pressure currently applied to the heating branch by the engine-side coolant pump. This is particularly advantageous where high accuracy of the set heating volume flow with minimal electrical output is important.

The component according to 4th is in particular in conjunction with the measures according to the invention, which are limited to heating coolant throughputs that are much lower than the coolant throughputs in the bypass branch 6b present in the open state, can be implemented in a particularly compact and robust manner, combined with the corresponding cost advantages.

This is due, on the one hand, to the package advantages that result from the fact that the coolant line diameter to the heating heat exchanger can be selected to be smaller than half as large as the 16-22 mm customary today, in particular combined with correspondingly small bending radii. Almost even more important, however, is the advantage that results from the low power requirement of the el additional pump 2 due to the low coolant flow rates. Even with a delivery pressure of 2 bar, the hydraulic power at 2 l / min is only 6.7 W, combined with the corresponding advantages in terms of the size of the electric pump and the electric drive as well as in terms of power consumption. In particular, the power requirement is so low that already available power channels of the engine control are sufficient to carry out the switching function or, if necessary, the power control. In particular with regard to the particularly advantageous stepless power control of the electronic pump with pulse width control, the low basic power of the pump helps to control the additional waste heat of the switching transistors during the switching processes without additional structural effort.

Conventional coolant throughputs through the cabin heat exchanger of 15 l / min, for example, would result in an analogous procedure in addition to the considerable package disadvantages in a hydraulic energy requirement of 50 watts, which means 100 watts of power with an overall efficiency of the pump of 50%. Under the practical assumption of an average fuel consumption of 15kW in the ECE cycle, 40% internal efficiency of the engine and 60% efficiency of the generator, this 50W el.pump drive power would ultimately result in the hardly acceptable additional consumption of 1.4% (= (50 / 0.60 / 0.40) / 15000). In view of the already limited availability of electrical energy in vehicles, but also in view of the costs for the electronics with correspondingly powerful power transistors for switching or regulating the electrical pump, the cost-benefit balance when using conventional heating technology is not only significantly worse, but also it also does not allow the particularly efficient design in accordance with 4th .

Another refinement of this device shows 5 . Here is a second valve seat 65b It is certain that when the valve is fully open, for example when 115 ° C is exceeded, the bypass is partially closed again so that the coolant throughput through the vehicle radiator is maximized. Whether or not this supplement is required depends on the overall vehicle / engine system. It is advantageous to ensure that, even when the valve disk 6bv is fully deflected in the open position, a minimum leakage current ensures that the thermostat also in the event of a spring break or jamming in this position 6th always receives such a high coolant throughput that it opens the cooler circuit in good time for the next cold start.

In connection with the strategy according to the invention for varying the coolant flow through the engine, the heating system heat exchanger and ultimately also the vehicle radiator, the devices according to FIG 4th and 5 Not only is it a very compact package that safeguards all the desired fail-safe aspects, it also has the advantage that even when the engine speed is changed to very high or very low values for a short time, there are hardly any fluctuations in the coolant throughput through the heating system heat exchanger. This is important for comfort, among other things. In addition, it always remains in the hands of the engine control whether the vehicle radiator is opened by opening the bypass valve 6bv: On the one hand, cold coolant remains available from the cabin heat exchanger, which ensures that the thermostat remains closed, and on the other hand, the engine control can open the bypass at any time and provide the maximum cooling effect.

In partial load operating situations, where additional or complete heat dissipation at the vehicle radiator is required, the vehicle radiator takes over the tasks of the heat sink. Due to the increased flow temperature to the vehicle radiator, an improvement in the cooling effect is also achieved here, so that, in particular in the case of stop and go or vehicle standstill, less fan power is sufficient than in systems previously known from series applications. This improvement can also be used earlier or more frequently with the procedure according to the invention than, for example, with the electronic thermostats already known from series applications or other conceivable systems that do not allow the cabin heating to be ensured with very small coolant throughputs of, for example, only 2 l / min.

As already mentioned, the bypass valves are in accordance with 4-7 Also of interest in operating situations, where the cabin heating output is the focus of interest and less the fuel saving, and where the heat management by closing the bypass branch 6b helps to improve the cabin heating effect by minimizing the effective heat active engine mass. During the warm-up, situations can definitely arise in which the bypass is activated 6b For example, it has to be opened at high engine load or engine speed. As was shown using the example of the EGR cooler, the bypass valves according to the invention also offer the necessary flexibility here to accomplish this without fluctuations in heating comfort. In addition, even when the bypass branch is open, in conjunction with a highly efficient cabin heat exchanger and low coolant throughput, they still allow the waste heat from the EGR cooler to be focused on the cabin and thus above-average cabin heating. The same applies if, in addition to or in place of the EGR cooler, another heat source, for example an exhaust gas heat exchanger instead of the EGR cooler according to 2 , is involved.

Although the procedure according to the invention and its special components are currently primarily based on applications with conventional expansion material actuators as an independent drive for the radiator thermostat 6th aim, an application of the inventive idea to other drive forms and types of radiator thermostats, in particular also with electronic actuators controlled by the engine control as a thermostat drive, such as the rotary slide valve described above, is advantageous. This applies in particular to the flexibility with regard to the optimal engine cooling as well as the robustness of the overall system in terms of component aging and sudden changes in driving operations and especially the potential utilization with regard to the heating and the package of the heating cables.

In this case, it should be noted in particular that the safety features with regard to excessively high coolant outlet temperatures from the engine or EGR cooler in the inventive configuration of the devices according to FIG 4-7 not by a motor-controlled switching function of the bypass flow within the instead of the thermostat 6th used rotary slide valve can be deactivated. To this end, it is particularly advantageous to work with two parallel bypass lines. 8th shows, starting from 4th a corresponding adaptation of the bypass valve. The first bypass line 68 is used here for temperature protection and in a position that cannot be locked by the rotary valve as a thermostat replacement 6th used rotary slide valve or arranged at the pump inlet, e.g. as in 3rd shown. The rotary slide valve then takes over in a known manner, based on data from the engine control, in addition to regulating the coolant flow through the radiator 6th also the partial or complete blocking of the second bypass branch by means of a corresponding rotary position 80 . The expansion element 6bs takes on the task of additional protection by opening the valve 6bv and the first bypass line 68 .

The el. Switching function 63 of the external bypass valve 6bv with the magnet 6bf is in 8th as multiple redundant safeguards and, if necessary, for particularly sensitive flow control, this can also be omitted if the rotary slide valve is appropriately precise and reliable. The not inconsiderable additional expense for this design of the engine and vehicle cooling system using a rotary slide valve as a thermostat replacement and an additional external bypass branch with a bypass valve is offset by a potential, albeit relatively small, by means of the most homogeneous engine temperatures possible with a warm engine being somewhat closer to the physical Limits regarding the maximum engine component temperature, especially in the increased partial load, to go.

Alternatively, instead of the rotary slide valve, a simple two-way valve as a thermostat set or an electrically heated thermostat, ie a thermostat with an opening temperature that is still variable even with very high coolant throughputs, can be used, so that the bypass valve according to 4th with only one bypass connection 68 sufficient.

The experimental quantification of the additional advantage that can be achieved with such additional effort is difficult and strongly dependent on the overall engine / vehicle system. Previous tests have shown that the increase in the heat transfer coefficient in particular at the higher coolant throughputs required to maximize the coolant temperature everywhere in the engine has a strongly counterproductive effect on the increase in the component temperature that is ultimately sought. In this context, the cost benefit analysis clearly speaks in favor of the variant with retention of the expansion thermostat 6th , but this can change depending on the development of fuel prices and potential future changes to the engine, such as the omission of the FEAD when using electronic engine cooling water pumps 6th also change in the future.

1-3 show application examples for the procedure according to the invention, with the reflux of the heating circuit 4a to the thermostat 6th in practice this usually takes place via a relatively long coolant line. Against this background, it is particularly attractive that the preferred variants according to the invention manage with very small line cross-sections. In particular, this results from the complete closing of the bypass branch 6b the possibility of largely eliminating its heat-active mass. At the same time, the complete closing of the bypass allows a very sensitive control of the total coolant throughput through the motor with a low throughput. Last but not least, this is very important with a view to optimizing the fuel-saving potential: Known systems, especially those with the rotary slide multi-way valve, require extremely precise positioning as well as extremely fast response when the engine speed varies. In view of the aging of the sealing edges of the rotary valve, in view of the aging of the engine coolant pump and in particular in view of the manufacturing variations of the engine pumps in interaction with the engine-side manufacturing tolerances, ensuring a robust overall system is associated with not inconsiderable expense.

With the procedure according to the invention, on the other hand, by closing the bypass and using the flow control means in the heating circuit, it is also possible in the range between 0 and 2 l / min to set the total coolant flow through the engine very precisely, reproducibly and with little sensitivity to the engine speed.

This particularly advantageous property is retained even if the return flow from the heating heat exchanger is integrated into the common housing of the bypass valve 6bv. As an example for the in 4-8 shows bypass valve variants shown 9 a corresponding integration of the Heating return by means of the connection 80 . This embodiment of the bypass valve offers the advantage of a particularly compact design. Even if the package is already very cheap in view of the small coolant line diameter, this is an additional simplification, since in particular fewer or no fastening positions are required for the heating return line. This advantage is offset by a certain disadvantage, which results from the fact that the heat-active mass of the bypass branch must also be heated up during warm-up. This has relatively little effect on the heating output, especially in the case of a very high temperature drop with high heating output, and somewhat more in the statutory emissions test without cabin heating. However, these effects are of an order of magnitude that, depending on the bypass line cross-section and depending on the package situation, the execution according to 9 is preferable. Even without the integration of the electronic coolant pump 2 and even more so with their integration, the use of highly efficient cabin heat exchangers and small heating line diameters is very advantageous for minimizing the size of the valve, for minimizing the line costs and for minimizing the heat-active masses.

The devices according to the invention are distinguished in particular by a very high level of operational reliability, even if individual components fail. For example, the expansion element 6bs takes over the safety monitoring against overheating in particularly safe embodiments.

1. 1. Bei geschlossenem Bypass 6b stellt die el. Pumpe 2 einen so solchen Kühlmitteldurchsatz im Heizungszweig ein, dass die Kühlmittel- oder Motorbauteiltemperatur einen ersten Grenzwert nicht überschreitet.
2. 2. Stellt die Motorsteuerung fest, dass der erste Grenzwert überschritten wird, so wird der Kühlmitteldurchsatz durch den Motor durch schrittweites oder gepulstes Öffnen des Bypassventils 6b solange erhöht, bis dieser Grenzwert wieder unterschritten wird.
3. 3. Stellt die Motorsteuerung fest, dass der erste Grenzwert permanent überschritten wird, so wird der Kühlmitteldurchsatz durch die Kabinenheizung unabhängig von der vom Klimarechner vorgegebenen Stellung auf erhöhte Werte eingestellt. Die luftseitige Temperaturregelung kompensiert gegebenenfalls die Luftaustrittstemperatur mittels des luftseitigen Bypassklappe, soweit dies möglich ist, so dass die Auswirkungen auf den Heizkomfort klein gehalten werden.
4. 4. Reicht die Vorgehensweise aus 3. nicht, so erfolgt ab einem zweiten Grenzwert ein vollständiges Ausschalten der Kabinenheizung, wiederum indem die Motorsteuerung den Klimarechner übersteuert.
5. 5. Sind Maßnahmen gemäß 3. und/oder 4. notwendig geworden, so wird dies in der Fehlerdiagnose abgespeichert und bei wiederholtem Auftreten dem Fahrer angezeigt.
6. 6. Als zusätzliche Absicherung kann wahlweise ein Dehnstoffaktuator 6bs eingesetzt werden, der den Bypass 6b öffnet. Die Öffnungstemperatur wird dabei bevorzugt so gewählt, dass sie erst nach dem Aktivieren der Schritte gemäß 3. und 4. eingreift, so dass eine sichere Fehlerdiagnose möglich ist.

A particularly advantageous hierarchy for safety monitoring in the partial engine load looks like this:

1. 1. With the bypass closed 6b sets the el. pump 2 such a coolant throughput in the heating branch that the coolant or engine component temperature does not exceed a first limit value.
2. 2. If the engine control determines that the first limit value has been exceeded, the coolant throughput through the engine is increased by opening the bypass valve step-by-step or pulsed 6b increased until the value falls below this limit again.
3. 3. If the engine control determines that the first limit value is permanently exceeded, the coolant throughput through the cabin heater is set to increased values regardless of the position specified by the climate computer. The air-side temperature control compensates, if necessary, the air outlet temperature by means of the air-side bypass flap, as far as this is possible, so that the effects on heating comfort are kept small.
4. 4. If the procedure from 3. is not sufficient, the cabin heating is switched off completely from a second limit value, again in that the engine control overrides the air conditioning computer.
5. 5. If measures according to 3 and / or 4 have become necessary, this is stored in the error diagnosis and indicated to the driver if it occurs repeatedly.
6. 6. As an additional safeguard, an expansion material actuator 6bs can be used to control the bypass 6b opens. The opening temperature is preferably selected in such a way that it only intervenes after the steps according to 3 and 4 have been activated, so that a reliable error diagnosis is possible.

However, this is just one of the many possible security strategies. Thus, the expansion material actuator 6bs can alternatively also be used to provide a temperature-controlled flow in the bypass branch as soon as the first limit value is reached 6b so that the electrical actuation of the bypass valve is only required to quickly switch off the hot cooling. If necessary, the electrical switching function of the bypass valve 6bv can even be omitted and, for this purpose, a very strong increase in the coolant flow in the heating circuit can be activated by means of the motor control.

In this context, the additional protection, in particular, is extremely robust, which is achieved by the optional overriding of the air conditioning computer by the engine control 20th with regard to the heating power extraction results: Even if the electrical actuation of the bypass valve 6bf fails, the superimposed switch-off by means of the expansion material actuator 6bs and even if the bypass valve 6bv is jammed in any position, for example in the configuration according to 5 , it is thus ensured that the motor control 20th the radiator thermostat if there is a risk of overheating 6th can open by activating the flow in the heating circuit but does not allow heat for heating purposes.

In other words, the protection against overheating, as it is realized in particular with the bypass valve 6bv with electronic actuator 6bf and expansion material actuator 6bs, is in accordance with the aspect of multiple protection and in view of the low production costs for heating and cooling devices with bypass valves 4-9 very advantageous, but actually not absolutely necessary with regard to sufficient operational safety.

If the described interactions are taken into account, the electronic actuator 6bf or the expansion material actuator 6bs can optionally be dispensed with with a correspondingly networked hierarchy between engine control and air conditioning control. In particular, in the event of an incorrect or implausible temperature measurement signal from the engine control, the actuator 6bf is automatically moved to the “bypass open” position by the engine control.

This conclusion with regard to further cost savings already applies to the particularly preferred procedure with small coolant line cross-sections and high pressure losses in the lines and the heating heat exchanger and even more so with a control range of the coolant throughput in the heating circuit from small to very high values.

This procedure that the engine control 20th for thermal protection in the event of a risk of overheating, the air conditioning control system overrides, in particular that it drives the power of an electric pump 2 increased and / or a flow control valve 15th opens and / or an air-side bypassing of the cabin heat exchanger 4th with the air temperature control 5 of the heater and in this way the radiator thermostat by specifically bringing about a reduced temperature drop at the heating heat exchanger with increased flow and / or reduced heating power consumption 6th opens when required, is for engine cooling and heating systems with and without bypass branch 6b applicable.

Use in engine cooling systems without a coolant bypass 6b is particularly advantageous if the basic design of the heating circuit allows relatively high coolant throughputs and means 15th and or 2 are available for sensitive control of the coolant throughput using the engine control. The flow control range should extend from low to relatively high values; a flow control range of 1-15 l / min and more is preferred. If the funds fail 15th or 2 For throughput control, a sufficiently large leakage flow of, for example, 1 l / min ensures that the thermostat is reliably opened by deactivating the heating on the engine control side 6th is possible. For additional protection, the component design according to the invention with a magnetic actuator 6bf and a superimposed expansion material actuator 6bs can also be used in an adapted form. To do this, for example, starting from the valve in accordance with 7th , just the drain 72 removed, the second sealing seat 65b omitted and the connection 68 is no longer the connection to the bypass but a new connection to the heating heat exchanger inlet. The leakage flow of, for example, 1 l / min is determined by means of a small hole in the valve seat plate 65 realized. Optionally, however, it is also sufficient to arrange the valve at a suitable point in the heating flow so that opening is also ensured by the thermosyphon effect when the cooling water temperature is too high. Compared to the technically more effective variants with a bypass branch 6b are such variants without a bypass branch 6b They are distinguished in particular by the fact that they still have an extremely good cost / benefit ratio, in particular for very simple engine concepts that are primarily geared towards high robustness at low costs and with moderate specific power.

Claims (12)

Method for operating a cooling and heating circuit for motor vehicles with an internal combustion engine (1) cooled by coolant with a vehicle radiator (8), a heating heat exchanger (4), coolant lines (4a, 6a) for conveying a liquid coolant in a radiator circuit from the internal combustion engine ( 1) to the vehicle radiator (8) and back to the internal combustion engine (1) and in a heating circuit from the internal combustion engine (1) to the heating heat exchanger (4) and back to the internal combustion engine (1), an air-side temperature control (5) of the air conveyed into the cabin, a thermostatic valve (6) which regulates the coolant throughput through the internal combustion engine (1) and the vehicle radiator (8) in order to control the coolant temperature, an electronic engine control (20) and a flow-limiting means (2, 15, 2) that can be influenced by the electronic engine control (20) +70) in the heating circuit, which controls the coolant throughput through the internal combustion engine (1) additionally varies depending on their cooling requirements, characterized in that the coolant throughput through the heating heat exchanger (4) and / or other coolant branches through which the thermostat valve (6) flows is so severely limited that a warm-up with the heating switched off during the Warm-up, no coolant at all or a very low coolant flow through the internal combustion engine (1) is set and that the cooling and heating circuit has a bypass circuit with a bypass branch (6b) through which the thermostat valve (6) can flow, which bypasses the vehicle radiator (8) and the one Additional valve (6bv) is assigned to additionally influence the coolant flow through the internal combustion engine (1). Method for operating a cooling and heating circuit for motor vehicles with an internal combustion engine (1) cooled by coolant with a vehicle radiator (8), a heating heat exchanger (4), coolant lines (4a, 6a) for conveying a liquid coolant in a radiator circuit from the internal combustion engine ( 1) to the vehicle radiator (8) and back to the internal combustion engine (1) and in a heating circuit from the internal combustion engine (1) to the heating heat exchanger (4) and back to the internal combustion engine (1), an air-side temperature control (5) of the air conveyed into the cabin, a thermostatic valve (6) which regulates the coolant throughput through the internal combustion engine (1) and the vehicle radiator (4) to control the coolant temperature, an electronic engine control (20) and a flow-limiting means (2, 15, 2) that can be influenced by the electronic engine control (20) +70) in the heating circuit, which controls the coolant throughput through the internal combustion engine (1) also varies depending on their cooling requirements, characterized in that the coolant throughput through the heating heat exchanger (4) and / or other coolant branches through which the thermostat valve is closed is so severely limited that in a warm-up with the heating switched off during warm-up, none at all Coolant or a very low coolant flow through the internal combustion engine (1) is set and that the throughput limiting means (15, 2 + 70) is opened by the engine control (20) so that the heating heat exchanger (4) is flown through, but by means of the air-side temperature control ( 5) no heat extraction for cabin heating purposes is permitted. Procedure according to Claim 1 or 2 , characterized in that the coolant flow through the internal combustion engine (1) is set to 0 to 2 l / min. Method according to one of the Claims 1 to 3rd , characterized in that an engine ventilation circuit with coolant line (9a) through which the thermostat valve (6) is closed is provided for conveying the liquid coolant from the internal combustion engine (1) to a coolant container (9) and back to the internal combustion engine (1), the coolant throughput in Heating heat exchanger and in the ventilation circuit during the warm-up as low as possible, preferably even temporarily equal to zero. Procedure according to Claim 2 , characterized in that the cooling and heating circuit has a bypass circuit with a bypass branch (6b) through which the thermostat valve (6) can flow, which bypasses the vehicle radiator (8) and to which an additional valve (6bv) is assigned, for additionally influencing the coolant flow through the Internal combustion engine (1). Method according to one of the Claims 1 to 5 , characterized in that parts of the combustion chamber walls become so warm that nucleate boiling begins locally in the water jacket. Procedure according to Claim 1 , characterized in that the throughput limiting means (15, 2 + 70) is opened by the engine control (20) so that the heating heat exchanger (4) is flown through, but by means of the air-side temperature control (5) no heat extraction for cabin heating purposes is permitted. Method according to one of the Claims 1 to 7th , characterized in that as the critical coolant outlet temperature from the internal combustion engine (1) is approached, the bypass volume flow is gradually increased. Method according to one of the Claims 1 to 8th , for motor vehicles with an air conditioning control, characterized in that the engine control (20) for thermal protection in the event of a risk of overheating the air conditioning control is overridden by opening the flow limitation means (2, 15, 2 + 70) and / or bypassing the cabin heat exchanger (4) on the air side with the heating device's air-side temperature control (5). Cooling and heating circuit for motor vehicles with an internal combustion engine (1) cooled by coolant a vehicle radiator (8), a heating system heat exchanger (4), Coolant lines (4a, 6a) for conveying a liquid coolant in a cooling circuit from the internal combustion engine (1) to the vehicle radiator (8) and back to the internal combustion engine (1) and in a heating circuit from the internal combustion engine (1) to the heating heat exchanger (4) and back to Internal combustion engine (1), an air-side temperature control (5) of the air conveyed into the cabin, a thermostatic valve (6), which is used to control the Coolant temperature regulates the coolant throughput through the internal combustion engine (1) and the vehicle radiator (8), an electronic engine control (20) and one of the electronic engine control (20) can be influenced Flow limiting means (2, 15, 2 + 70) in the heating circuit, which additionally varies the coolant throughput through the internal combustion engine (1) as a function of its cooling requirement when the heating is switched off, and one through which the thermostatic valve (6) is closed Bypass branch (6b) with an additional valve (6bv) which bypasses the vehicle radiator (8) for additional influencing of the coolant flow through the internal combustion engine (1). Cooling and heating circuit according to Claim 10 , characterized in that in the engine control (20) the method according to one of the Claims 1 to 9 is deposited. Motor vehicle with a cooling and heating circuit according to one of the Claims 10 to 11 .

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