WO2003056152A1

WO2003056152A1 - Method for controlling electrically-operated components of a cooling system, computer programme, controller, cooling system and internal combustion engine

Info

Publication number: WO2003056152A1
Application number: PCT/DE2002/003881
Authority: WO
Inventors: Manfred Schmitt; Peter Deuble; Karsten Mann; Oliver Kaefer
Original assignee: Robert Bosch Gmbh
Priority date: 2001-12-22
Filing date: 2002-10-15
Publication date: 2003-07-10
Also published as: EP1461516A1; DE50211857D1; EP1461516B1; DE10163944A1

Abstract

The invention relates to a method for controlling electrically-operated components of a cooling system for an internal combustion engine on a motor vehicle, whereby said components are controlled by a controller. The invention further relates to a computer programme for an internal combustion engine on a motor vehicle, a controller for controlling electrically-operated components of a cooling system for an internal combustion engine on a motor vehicle, a cooling system for an internal combustion engine, comprising controlled electrically-operated components and an internal combustion engine for a motor vehicle.

Description

Method for controlling electrically operable components of a cooling system, computer program, control device, cooling system and internal combustion engine

The invention relates to a method for controlling electrically actuatable components of a cooling system for an internal combustion engine of a motor vehicle, the components being controlled by a control unit. The invention further relates to a computer program for an internal combustion engine of a motor vehicle, a control device for controlling electrically operable components of a cooling system for an internal combustion engine of a motor vehicle, a cooling system for an internal combustion engine of a motor vehicle with controllable, electrically actuatable components and an internal combustion engine of a motor vehicle.

State of the art

DE 37 01 584 C2 discloses a device for actuating a blind arranged on the radiator of a water-cooled internal combustion engine of a motor vehicle. The radiator blind is connected to an electric motor via a drive shaft, making it possible to move the blind between two settings. Here, one setting releases the cooler completely and is therefore assigned to an upper operating limit temperature of the coolant and in the second setting the radiator blind is completely closed, which in principle is assigned to low coolant temperatures. The radiator blind is controlled depending on the coolant temperature and additionally by an expansion element that responds at high cooling water temperatures and releases a coupling so that the blind under load automatically reaches its radiator release position in order to damage the cooling system and / or at high cooling water temperatures to prevent the internal combustion engine.

From DE 37 38 412 AI a device and a method for engine cooling is known, in which a mechanical and an electric coolant pump are assigned to the engine to be cooled, the electric coolant pump being controlled by an electronic switching device. The delivery rate of the electric pump is determined depending on the operating parameters of the motor to be cooled and other sizes, while the mechanical pump is designed for a basic delivery rate. The cooling system according to DE 37 38 412 AI consists of two coolant paths, with a heat exchanger operated as a cooler being arranged in the first coolant path, the cooling capacity of which can be changed with the aid of a cooler blind and a fan or fan. A further heat exchanger is arranged in the second coolant path or alternatively in a separate coolant circuit, the waste heat of which is used for heating purposes or for further engine cooling. The second cooling circuit can be used in particular for engine cooling in that an air flap can be opened by the electronic switching device, the air flap blocking the heating air duct and one outdoors releases the air duct. In other words, the engine's waste heat is not released into the interior of the motor vehicle, but into the environment. In addition to the coolant temperature, the electronic switching device that controls the electric pump and the other components, blinds, blowers and mixing valves receives further information such as the engine operating temperature, the engine compartment temperature, temperatures of engine parts, the ambient temperature, engine speed, driving speed and a pressure signal from the coolant fed. With this information, the delivery capacity of the electric pump can be precisely adjusted to the required cooling capacity. When the engine is cold, the coolant bypasses the engine cooler. This measure ensures that the engine warms up to the operating temperature as quickly as possible, since an internal combustion engine has the maximum efficiency at the optimum operating temperature. The measurement of the driving speed has a particular influence on the actuation of the blind and the fan. At higher speeds, for example, it would be inappropriate to keep the blinds closed and to switch on the fan. Such inappropriate operating states can be identified and avoided with the electronic switching device. According to the device and the method for engine cooling according to DE 37 38 412 AI, a rapid achievement and precise maintenance of the coolant temperature is made possible. This keeps the motor in a temperature range with maximum efficiency. The rapid heating-up process reduces wear at low operating temperatures. The electronic switchgear also excludes non-sensible operating states. A thermal management system with its components was presented in a press release by Robert Bosch GmbH Stuttgart on the occasion of the IAA 2001. According to the press release, the prerequisites for a temperature control that is appropriate to the situation are electromotively driven, infinitely variable components: a water pump, proportional control valves, an adapted radiator fan and a radiator blind, all of which are controlled by electronics integrated in an engine control unit. Decoupled from the engine speed, this system controls coolant temperature and volume flow better than thermostatic and belt-driven water pumps. Adaptation to thermal changes in a matter of seconds, even when the engine is switched off, and permanent function monitoring avoid problems such as engines that run permanently "supercooled" and unnoticed overheating during peak load This results in combustion and thus reduced exhaust emissions, but also a reduction in consumption and increased heating comfort in the vehicle interior. Such a thermal management system can be flexibly expanded with additional components such as an electric auxiliary heater. Networking with electronically controlled air conditioning systems is possible.

DE 198 31 901 AI discloses a device for cooling an engine for a motor vehicle. In the disclosed cooling circuit of an internal combustion engine, the division of the coolant flows into individual partial circuits is not achieved via thermostatic valves as active elements, but via at least one further pump operated in addition to a main water pump. By using a the main water pump is supported in such an additional water pump. The main water pump can thus be operated with a smaller output or can be dimensioned smaller. According to DE 198 31 901 AI, it is also possible to use several pumps with similar performance in the coolant circuit, which then perform specially assigned cooling tasks. It is given as an example that the cylinder head of the engine is cooled separately and controllably or that individual cylinders are supplied with coolant by one pump each. This also gives you the option of specifically setting different temperature levels in the cylinders of the engine block. By using electric motor-operated, independent pumps that can be controlled independently of the speed of the motor, it is possible for the coolant flow to be divided into partial flows, each of which can be adjusted according to the thermal load on the motor. Compared to conventional devices, a more efficient and thus also more energy-saving form of engine cooling can be realized. DE 198 31 901 AI indicates that the adjustable pump enables the setting of a defined volume flow through the heat exchanger (heat exchanger for heating the passenger compartment) to be regulated in a simple manner. The switching and control processes in the cooling circuit are recorded by a higher-level control unit, the programming of which is operated as efficiently as possible with regard to the cooling of the engine and its energy consumption.

task

It is the object of the present invention to improve the control of electrically actuable components of a cooling system for an internal combustion engine of a motor vehicle compared to the prior art. Solution and advantages of the invention

The object is achieved by a method for actuating electrically actuable components of a cooling system for an internal combustion engine of a motor vehicle, the components being actuated by a control unit and the actuation being carried out by means of a pilot control. The control according to the invention by means of a pilot control improves the control of the electrically operable components compared to the prior art. By means of a pilot control, it is advantageously possible to adapt the control variables for the electrically actuable components to the new operating conditions immediately when the motor vehicle changes its operating point. A development according to the invention provides that controllers are superimposed on the pilot control. The superimposition of controllers can compensate for deviations from target values, that is to say from the desired optimal values, which are caused by factors that have not been taken into account, for example disturbance variables. In real operation of a motor vehicle, there are often rapid changes in the operating point, which must be reacted to quickly despite the system, which has a high dead time. Using the method according to the invention, very quick and very precise control of electrically actuable components of a cooling system for an internal combustion engine of a motor vehicle is possible, which leads to good control quality.

The preferred development of the method according to the invention provides that the superimposition of the controllers is carried out by prioritizing the controller values. In this way, the advantages of a pre-control value (control energy-optimized pre-control values, lower controller effort, etc.) combined with the advantages of controller values linked with a priority. Prioritization can, for example, only forward the portion of a controller value for activation to the electrically actuable component, which, according to the priority, leads to a minimum actuating energy with a view to the optimal overall efficiency of the entire cooling system or even the entire motor vehicle. In other words, the signals from the controller interventions are modified in such a way that all control objectives are met with a higher degree of efficiency. It would also be conceivable to use adaptive methods for this.

An advantageous development of the method according to the invention provides that an operating point-dependent characteristic diagram is provided for the respective component in order to precontrol each individual component. These pilot control maps can be so marked that for each operating point of the motor vehicle there is a configuration of the electrically operable components that is close to the optimum energy. It can thus advantageously be prevented that an electrically actuatable component that has a higher actuation energy requirement than another electrically actuatable component is actuated, although actuation of the other electrically actuatable component with less actuation energy expenditure has the same result for the cooling system of the internal combustion engine would lead.

A preferred development provides that a separate pilot control and a separate controller are provided for each electrically actuable component. This offers the advantage that, in cases where different disturbance variables exist for the various electrically actuable components, they are individually tailored to the respective one Disturbance can be responded to in any

Operating situation to ensure optimal and fast control of the electrically actuated components.

An advantageous development of the method according to the invention provides that the actuation of the electrically actuable components determines operating point-dependent setpoints for at least one of the following variables from operating point-dependent maps: engine temperature, cooling reserve differential temperature or engine differential temperature. A coolant temperature at the engine outlet or temperatures inside the engine can be used as the engine temperature, for example. The engine differential temperature can be defined, for example, as the temperature difference between the coolant inlet and outlet at the engine or the temperature difference between a critical internal engine temperature and a coolant temperature at the engine inlet or the temperature difference between two internal engine temperatures. The cooling reserve differential temperature is understood to mean a differential temperature which is related to a cooling reserve, i. H. For example, the temperature difference over an engine cooler or the temperature difference between a coolant at the radiator outlet and the engine temperature or the coolant temperature difference between the radiator outlet and the engine inlet. Similar to the torque reserve in an engine control system, an operating point-dependent cooling capacity reserve ensures that, for example, a sudden increase in engine load can be reacted as dynamically as possible.

The specification of the above-mentioned setpoints motor temperature, cooling reserve differential temperature or engine differential temperature leads to quick and safe control of the electrically operated components. The setpoint for the cooling reserve differential temperature is advantageously taken from a map which is at least dependent on the operating state of the internal combustion engine, in particular an engine load and / or the driver type and / or a driving situation and / or a cooling circuit state. In this way, practically "controllable disturbance variables" are advantageously incorporated into the control concept.

An advantageous further development of the structure of pilot control with a superimposed controller provides that the controller gains are dependent on at least one coolant volume flow. This is advantageous because the transport times and time constants and thus the reaction times in the cooling circuit system change depending on the volume flow. For example, a so-called gain scheduling PID controller can be used. The controller gains are advantageously determined with the aid of an observer of the respective volume flows.

A further advantageous development of the method according to the invention provides that the electrically operable components are controlled in such a way that a minimum volume flow of a coolant that is dependent on the operating point is ensured. By taking a minimum volume flow into account, damage to the engine or the components of the cooling circuit system is reliably avoided, since the formation of so-called hot spots (overheated points) is avoided.

According to an advantageous further development, a radiator fan and a radiator blind are actuated as a common component from the control. This is possible because each of these electrically operated components (Radiator fan and radiator blind) can only increase or decrease the air mass flow.

Of particular importance is the implementation of the method according to the invention in the form of a computer program which is provided for an internal combustion engine, in particular a motor vehicle. The computer program has a sequence of instructions which are suitable for carrying out the method according to the invention when they are executed on a computer. Furthermore, the sequence of commands can be stored on a computer-readable data carrier, for example on a floppy disk, a compact disk, a so-called flash memory or the like.

The computer program can optionally be sold together with other computer programs as a software product, for example to a manufacturer of control units for internal combustion engines. The software product can be transmitted by sending a floppy disk or a CD, the content of which the control device manufacturer then transfers to the control device. It is also possible for a flash memory to be sent to the control unit manufacturer, which the manufacturer installs directly in the control unit. It is also possible that the software product has an electronic

Communication network, in particular via the Internet, is transmitted to the control unit manufacturer. In this case, the software product as such - that is, independent of an electronic storage medium - represents the sales product. In this case, the control device manufacturer downloads the software product, for example from the Internet, in order to then save it, for example, on a flash memory and into the control device use. The computer program can also be sold as a separate software product that a manufacturer of control units transmits into the control unit together with other software products from other (third-party manufacturers). In this case, the software product according to the invention is a module that is compatible with other modules from other manufacturers.

In all these cases, the invention is implemented by the computer program, so that this computer program represents the invention in the same way as the method for which the computer program is suitable for execution. This applies regardless of whether the computer program is stored on a storage medium or whether it is present as such - that is, independently of a storage medium.

The object is further achieved by a control device for controlling electrically operable components of a cooling system for an internal combustion engine of a motor vehicle and wherein the control device for controlling the components has at least one pilot control.

The object is further achieved by a cooling system for an internal combustion engine of a motor vehicle with controllable, electrically actuatable components, the components being controlled by a control device and the control device having at least one pilot control for controlling the components.

Finally, the object is achieved by an internal combustion engine of a motor vehicle, in which electrically operable components of a cooling system for the internal combustion engine can be controlled, the components being controlled by a control device and the control device for Control of the components has at least one pilot control.

Further features, possible applications and advantages of the invention result from the following description of exemplary embodiments of the invention, which are shown in the figures.

Embodiments of the invention

FIG. 1 shows a first exemplary embodiment of the method according to the invention,

Figure 2 shows a second, more concrete embodiment of the method and

Figure 3 shows an embodiment of the cooling system according to the invention.

A cooling circuit usually includes a heat source to be cooled, e.g. the vehicle engine, which are cooled by means of a cooling medium by free or forced convection. The temperature difference above the heat source depends on the heat input and the size of the volume flow of the coolant, while the absolute temperature of the cooling medium is determined by the heat input from the heat source, the heat dissipation via coolers in circulation and the heat capacities of the materials.

Mechanical water pumps currently used in motor cooling systems of motor vehicles, which are driven by V-belts from the crankshaft of the engine, are dimensioned so that in the most critical operating condition, i.e. when driving uphill with medium speed, high load and low vehicle speed, no impermissible Temperature difference over the engine arises. The mixing ratio between a bypass line and the cooler branch is set by an expansion-controlled thermostatic valve depending on the coolant temperature. This valve is dimensioned so that it is fully open from a fixed temperature. This prevents impermissibly high coolant temperatures.

In order to decouple the volume flow from the speed, a controllable coolant pump is used according to the invention. In order to be able to regulate the temperature level, the thermostat is replaced by an adjustable proportional valve. Furthermore, according to the invention, continuously variable cooling fans and / or cooling blinds are provided for the system. The cooling system according to the invention enables the engine cooling system to be controlled or regulated as required, with the aim of reducing fuel consumption and reducing emissions, or of observing exhaust gas limit values and also of increasing comfort. Critical limits of the component load are not exceeded. This is achieved through the optimization of the coolant volume flow and the load-dependent regulation of the temperature level of the engine. So the coolant temperature e.g. raised in partial load operation and lowered in full load operation. The associated higher filling level also increases the engine power.

The invention represents a logic integrated in the engine control, which carries out the distribution of the heat flows in an intelligent and priority-dependent manner by means of a precontrol and a superimposed control. This is explained in more detail in the context of the description of FIGS. 1 to 3. The invention achieves optimal operating conditions for the internal combustion engine by a specific engine temperature (temperature of the coolant at the engine inlet or outlet, the temperature of highly loaded internal engine components such as cylinder head temperature between the exhaust valves, temperature in the cylinder web, etc.), the coolant volume flow and its distribution on different parallel branches and the air mass flow through the cooler can be adapted exactly to the respective operating conditions.

FIGS. 1 and 2 show exemplary embodiments of the method according to the invention, with FIG. 1 representing a general and FIG. 2 a special exemplary embodiment.

In the method according to the invention according to FIG. 1, the actual or measured value acquisition is started in a step 101. Values such as engine speed, engine load, cooling circuit status, vehicle speed, driver type, vehicle status, temperature at the radiator outlet, temperature at the engine inlet, temperature at the engine outlet or temperature of the engine itself are determined.

The vehicle state is understood to mean different vehicle state variables (eg vehicle speed, acceleration, load, incline, etc.). It is within the scope of the invention to modify the exemplary embodiments in such a way that future, expected variables are also taken into account. For example, an upcoming uphill or downhill ride could be taken into account by means of a navigation system. If, for example, a downhill run is imminent, the system does not need to be cooled down as much and it could result in an energy-intensive start-up of the coolant pump and Radiator fans are dispensed with, since a short-term reduction in the coolant temperature can be achieved simply by intervening in the radiator mixing valve.

Following step 101, target values are formed in step 102. These can be, for example, target values for the engine temperature, for the engine differential temperature or the so-called cooling reserve, which represents the differential temperature from the target value of the engine inlet temperature and the radiator outlet target temperature. These target values are taken from the characteristic diagrams stored in the memory of the control unit in accordance with the previously determined actual values. Following the formation of the setpoint value, the setpoint / actual deviation of the previously determined setpoint values is determined in step 103. These target / actual deviations in accordance with step 103 are used as controller input variables for determining the controller values in step 104. If necessary, the controller values are determined taking into account further parameters, for example the coolant volume flow. PI controllers (proportional integral controllers) or PID controllers are preferably used as controllers. The controller values determined in step 104 are linked with a prioritization in a subsequent step 105. The determination of the prioritization, which takes place in steps 111 and 112, will be discussed later.

In parallel to steps 102 to 105, a pre-control value for the respective component is determined in a step 106 following step 101. This can be, for example, a pilot control value for a radiator mixing valve, a coolant pump, a radiator fan or a radiator blind. The pilot control values are taken from the characteristic maps stored in the memory of the control unit in analogy to the target values in accordance with certain input parameters. The pilot control values after step 106 are linked in a step 107 with the prioritized controller values. This means that in addition to the pre-control values after step 106, step 107 also receives the prioritized controller values after step 105. The linking of the pilot control values with prioritized controller values after step 107 can be additive or multiplicative. Following step 107, the previously determined control signals are filtered in step 108. Finally, in step 109 following step 108, the respective control signal for the various electrically actuable components, for example the cooler mixing valve, the coolant pump, the radiator fan or the radiator blind, is obtained. In step 110, which follows step 109, the components are finally controlled directly or indirectly (via output stages) by the engine control unit in accordance with the determined control signal.

The control signal after step 109 is also fed to a step 111, to which the actual or measured values determined in step 101 are also fed. On the basis of the actual or measured values supplied from step 101 and the control signals transmitted from step 109, the respective actuating energy of the respective electrically actuable component is determined in step 111 by means of an observer. Following step 111, a prioritization is carried out in a step 112 on the basis of the previously determined actuating energy of the respective electrically actuatable component and further input variables, such as the vehicle state, in accordance with the necessary actuating energy of the various electrical components. Particular attention is paid to the water pump and the fan, since these electrically operated components represent those with the greatest energy requirements. The The initial value of the prioritization after step 112 flows into step 105, which has already been described above.

FIG. 2 shows a practical example or a practical embodiment of the exemplary embodiment of the method according to the invention for controlling electrically operable components of a cooling system for an internal combustion engine of a motor vehicle, which is described more generally in FIG. The various areas of the method corresponding to FIG. 1 are recorded on a line in the upper area of FIG. The first area of the “actual values” corresponds to method step 101 according to FIG. 1. The second area “feedforward control” corresponds to method step 106 according to FIG. 1. The area “setpoints” corresponds to method step 102 according to FIG. 1. The area “controller” corresponds to the method steps 103 and 104 according to FIG. 1. The subsequent “prioritization” area corresponds to method steps 112, 105 and 107 according to FIG. 1. The “filtering” area corresponds to method step 108 and the last area “activation” corresponds to method steps 109 and 110 according to FIG 1. Method step 111 according to FIG. 1 corresponds to method step 233 according to FIG. 2, which will be discussed in more detail later.

In FIG. 2, the process begins with the actual or measured value acquisition. As shown in FIG. 2 on the left edge of the figure, the values of engine speed, engine load, cooling circuit condition, engine outlet temperature T_MA, the speed of the vehicle V_vehicle and the driver type are recorded. The driver type value, here a distinction is made, for example, between a sporty and a more conservative driver, can usually be taken from a transmission control system where this signal is present. The target engine temperature Tmot, target is determined in a step 201 from the input variables engine speed and engine load. The desired engine temperature is taken from a map stored in the memory of the control unit of the motor vehicle. The target value for the engine temperature Tmot, target determined in step 201 is passed to a connection point 202, at which the target / actual deviation is determined. For this purpose, the current measured (or otherwise calculated or determined) engine temperature Tmot is subtracted from the previously determined target engine temperature Tmot in step 202 or at node 202. The result of this target / actual deviation determination in step 202 is fed to a controller 203. The controller can be, for example, a proportional integral controller (PI), a PID controller or a fuzzy controller. A signal is fed to the controller as a further input variable, which makes a statement about the coolant volume flow. This signal is determined in a step 233, which will be discussed further below. After the controller value has been determined in step 203, the result of the prioritization is supplied in step 204. Here the controller value is linked to a prioritization after step 203. The prioritization of the individual electrically actuable components was previously carried out in step 234, which will also be discussed later. The linkage is, for example, multiplicative, as a result of which the previously determined controller value can drop to zero in extreme cases. In parallel with method steps 201, 202, 203 and 204, a pilot control value for a cooler mixing valve X_valve (see reference numeral 302 in FIG. 3) is determined from the input variables engine load, engine speed and cooling circuit state in a step 205. The result of step 205, which becomes the predetermined pilot value for the radiator mixing valve X valve to a node 206, to which the prioritized controller value after step 204 is also supplied. At point 206 or step 206, the link is now made, for example by adding, the pilot control and the prioritized controller value for the cooler-mixing valve. The result of this step 206 is fed to filtering in step 207. The filtering can take place, for example, in that the change in the control value for the cooler mixing valve is limited by an upper limit. This avoids reacting too quickly to sudden load changes. The control signal for the cooler-mixing valve 208 results as a result of the filtering after step 207, or in step 208 the cooler-mixing valve is controlled with the previously determined control signal. Steps 201 to 208 thus represent the determination of the control signal for the cooler mixing valve.

The determination of the control signal for the electrically operable coolant pump (reference numeral 307 in FIG. 3) is described below in steps 209 to 219. In a step 209, a setpoint for the engine differential temperature ΔTmot, target is first determined from a characteristic diagram, which is stored in the memory of the control unit, from the input variables engine load and temperature at the engine output T_MA. This determined motor difference setpoint value ΔTmot, should be fed to a node 210. The setpoint / actual deviation of the engine differential temperature ΔTmot, setpoint is determined at this node 210 in the real, measured value of the engine difference temperature setpoint value ΔTmot, setpoint supplied from step 209

Motor differential temperature (temperature at the motor output minus temperature at the motor input, T_MA - T_ME) is subtracted. The result from step 210 is fed to a controller in step 211, which is used, for example, as a PI controller can be executed. The controller value after step 211 is fed to a link point 212, where the controller value after step 211 is linked to a prioritization. This prioritization is determined in a step 213 and is based on the controller value after step 203 and the prioritization after step 234. The link in step 212 is generally carried out multiplicatively. The result of the link between the controller value after step 211 and the prioritization after step 213 is fed to a further link point 214. The further input variable of node 214 is the pilot control value of the control variable (eg number of revolutions) of the coolant pump U_Pumpe, which is supplied by a step 215. In this step 215, based on the input variables engine load and temperature at engine output T_MA, the pilot control value for the coolant pump U_Pumpe is taken from a map stored in the memory of the engine control unit. The result of the link in node 214 or in step 214 is fed to a maximum value selection 216. In addition to the input signal from node 214, a further input signal is fed to the maximum value selection 216. This further input signal for the maximum value selection 216 is the minimum volumetric flow taken in step 217 from the input signals engine load and temperature at the engine output T_MA from a map in the memory of the engine control unit, which ensures a certain minimum volumetric flow of the coolant. This maximum value selection in step 216 ensures that a certain minimum volume flow corresponding to the respective operating situation is ensured for safety reasons. The result of the maximum value selection after step 216 is fed to a filter in step 218. As a result of the filter in step 218, which is equivalent to step 207, the drive signal for the coolant pump is available in step 219. By realizing a Minimum volume flow 217 in conjunction with the maximum value selection 216, the controller intervention 211 can practically only increase the control signal of the pump 219. The control quality of the controller 211 for the engine differential temperature is improved by the pilot control 215.

In the following steps 220 to 227, the control signal for the radiator fan (reference number 317 in FIG. 3) is generated. In a step 220, a pre-control value for the control of the fan U_Lüfter (for example number of revolutions or control voltage) is determined on the basis of the input variables engine load and vehicle speed V_vehicle from a map stored in the memory of the engine control unit. This pilot control value for controlling the fan after step 220 is fed to a link point 221, to which a prioritized controller value is also fed after step 222. The prioritization unit 222 is supplied with input values of the controller output after step 203, the output signal of the prioritization after step 234 and the output of a controller unit 227, which will be discussed further below. Based on these input variables, a prioritized controller value is generated in step 222, which, together with the precontrol value for controlling the fan, merges node 221 after step 220. The output of node 221 is fed to a filter 223, which functions analogously to the filters after steps 207 and 218. The output signal of the filter 223 is the control signal 224 for the engine fan of the cooling system.

As described above, the prioritization step 222 was also supplied with the output signal of a controller 227, which will now be explained in the following: Based on the input variables engine load,

In a step 225, the cooling circuit status and driver type are determined from a map stored in the memory of the engine control unit, a target value for the temperature difference across the cooler ΔT_cooler, target (temperature difference across the cooler ΔT_cooler, target = engine output temperature T_MA - temperature at the radiator output T_KA). The target value for the cooler differential temperature .DELTA.T_cooler, determined after step 225, is fed to a node 226, at which the cooler reserve is to be subtracted from the cooler differential temperature setpoint. The cooling reserve is generally to be understood as the difference between the engine temperature Tmot and the temperature at the radiator outlet T_KA (in particular e.g. T_MA, Soll-T_KA, Soll or T_ME, Soll-T_KA, Soll). The result of this connection point 226 is fed to the controller already mentioned in step 227. As a further input variable, a signal representing the coolant volume flow from step 233 is fed to the controller in step 227. The controller after step 227 can be designed as a PI controller, for example.

Steps 228 to 232 represent the control signal determination for a radiator blind (reference symbol 316 in FIG. 3). Here, the output of the controller is fed to a prioritization 228 after step 227. As a further input variable, the prioritization in step 228 is supplied with the output signal of the prioritization 234, which will be discussed in more detail later. The output signal of the prioritization after step 228, that is the prioritized controller value after step 227, is fed to a node 230. As a further input signal of the connection point 230, in a step 229, the input signals engine load and vehicle speed V_vehicle are used to generate a pilot control value for the activation of the Radiator blind X_Jalousie determined from a map. The link after step 230 can be additive. The output signal of the link after step 230 is fed in step 231 to a filter analogous to steps 207, 218 and 223 in step 231. The output signal of the filter after step 231 finally represents the control signal 232 for the radiator blind.

Steps 233 and 234, to which reference has already been made, are explained below. Step 233 represents an observer to whom, in addition to the engine load, the control signals for the cooler mixing valve 208, for the coolant pump 219, for the cooler fan 224 and for the blind 232 are supplied. Using the supplied data, the observer determines the currently prevailing coolant volume flow and makes it available as an output signal. As already described above, this output signal is fed to the controllers 203 and 227. The actuating energy required for the respective components is output as a further output variable of the observer after step 233 and transferred to the prioritization in step 234. The vehicle status is fed to the prioritization in step 234 as a further input variable. Knowing the state of the vehicle and the respective actuating energy, an individual priority signal is generated in step 234 for the respective electrically operable components and transmitted to the respective prioritizations in step 204, step 213, step 222 and 228.

A complete concept comprising pilot control, prioritized controller values and filters for the optimal control of electrically actuable components in a cooling system for a motor vehicle has thus been described. Figure 3 shows an embodiment of a device according to the invention. A block 300 is shown as the central unit, which is intended to symbolize the engine block of an internal combustion engine. A cooling medium that serves to cool the engine block 300 flows out of the engine block 300 via a line 301. This cooling medium in line 301 is passed via a cooler mixing valve 302 into a line 303. The coolant continues to flow from a line 303 into a cooler 304. After the cooler 304, the coolant flows through a line 305 in the direction of the coolant pump 307. The coolant pump 307 pumps the coolant back into the engine block 300 via a line 308 Part of the cooling medium from line 301 is conducted from the cooler mixing valve 302 via a line 306, the so-called bypass line, past the cooler 304 directly into line 305.

Part of the cooling medium that flows into the engine block 300 via the line 308 does not leave the engine block 300 via the line 301, but via a line 309, which leads to the heating heat exchanger 310, which provides for the heating of the passenger compartment. From the heating heat exchanger 310, the cooling medium flows back into line 305 via a further line 311 and opens there directly in front of the coolant pump 307.

The following temperature sensors are arranged in the cooling system: a temperature sensor 312 detects the engine temperature Tmot, a temperature sensor 313 detects the engine output temperature T_MA, a temperature sensor 314 detects the

Radiator outlet temperature T_KA and a temperature sensor 315 detect the engine inlet temperature T_ME. Tmot could, for example, be an internal coolant or component temperature or the engine outlet temperature. Further important components of the cooling system are an electrically operable radiator blind 316 and a radiator fan 317. The radiator blind 316 serves to isolate the radiator 304 from the cooling wind in certain operating situations, whereas the radiator fan 317 leads to increased cooling of the cooling medium in the radiator 304.

Also shown is a control unit 318, which is generally the engine control unit of the internal combustion engine and which, in addition to controlling the cooling system, takes on further tasks, such as controlling the engine combustion. The signals from the temperature sensors 312, 313, 314 and 315 are fed to the control unit 318 via the signal lines 321, 323, 324 and 326. At the same time, control unit 318 outputs output signals for actuating electrically operable components 302, 304, 316 and 317. Specifically, these are the control signal for controlling the cooler mixing valve 302 via the signal line 319, the signal line 320 for controlling the radiator blind 316, the signal line 322 for controlling the cooler fan 317 and the signal line 325 for controlling the coolant pump 307.

In the engine control unit 318 there is a memory element, not shown in FIG. 3, in which the characteristic diagrams shown in FIG. 2 are stored. The other functions shown in FIG. 2, such as feedforward control, controller, prioritization, observer, maximum value selection and filter, are all functionally integrated in control unit 318. It is not essential to the invention whether the functions are integrated in the control device as hardware, that is to say via circuits, or via software. A software integrated in the control unit 318 which is used to carry out the method according to the invention for controlling electrically operable components of the cooling system is suitable, thus fulfills the invention in the same way as a hard-wired circuit model.

The desired setpoint temperature of the cooling medium or a temperature internal to the engine is regulated at any time by the method according to the invention or the cooling system according to the invention, this regulation being implemented with minimal expenditure of actuating energy. In the characteristic diagrams stored in the control unit 318, setpoints are predefined in accordance with the cooling circuit states for the overall energy-optimal state of the vehicle. The pilot control indicators of the controller structure are marked so that for each operating point there is a configuration of the actuators that is as close as possible to the energetic optimum and with which the target values are achieved as far as possible. Any necessary corrections are made through controller interventions. The prioritization decides whether and, if necessary, to what extent the control intervention is added to the control element as a control signal, or whether another control element is controlled instead or whether the current control deviation should not be reduced. The prioritization can also decide whether it is energetically sensible to implement the desired cooling circuit state from the current cooling circuit state. However, deviations from the target specifications are only permissible for less critical operating conditions.

In the prioritization, certain rules and information are taken into account, such as:

- The radiator fan may only be activated when the radiator mixing valve is open to the radiator by more than 80%. - The radiator blind must not be opened via an opening of, for example, x%, as long as the radiator mixing valve is open to, for example, y% of the radiator.

- The energy expenditure for increasing the cooling capacity by correspondingly changing the position of the electrically actuable components as a function of the cooling circuit state and operating state of the motor vehicle.

- Possibly . To improve the driving comfort of the radiator fan, it may only be switched on in certain engine speed ranges due to its high noise level.

- The prioritization of the control signals of the radiator fan and coolant pump components, relative to the other electrically operable components, are given higher priorities, since these have a particularly high power requirement. In other words, the radiator mixing valve and the radiator blind are opened first.

- The influence of the radiator blind on the cd value of the motor vehicle and the associated influence on the maximum driving speed of the motor vehicle and the consumption are taken into account.

The prioritization brings the control of the cooling system closer to the energetic optimum. The cooling system is - if possible - with a

Minimum coolant volume flow, the radiator fan switched off and the radiator blind closed as far as possible. The cooling capacity to be dissipated is preferably by the cooler valve or the cooler mixing valve is regulated. Only when the required cooling capacity can no longer be achieved with these specifications, is a combination of the position of the radiator blind, coolant pump and radiator fan optimized for the desired energy level.

The invention ensures that the component load and the formation of so-called hot spots do not go beyond the permissible level.

Claims

Expectations

1. A method for controlling electrically actuable components of a cooling system for an internal combustion engine of a motor vehicle, the components being controlled by a control unit, characterized in that the control is carried out by means of a pilot control.

2. The method according to claim 1, characterized in that the pilot control are superimposed.

3. The method according to claim 2, characterized in that the superposition is carried out by prioritizing the controller values.

4. The method according to claim 1, characterized in that an operating point-dependent map for the respective component is provided for pilot control of each individual component.

5. The method according to claim 2, 3 or 4, characterized in that a separate pilot control and a separate controller is provided for each component.

6. The method according to claim 1, characterized in that the control determines operating point-dependent setpoints for at least one of the following variables from operating point-dependent maps: engine temperature, cooling reserve differential temperature or engine differential temperature.

7. The method according to claim 2, characterized in that controller reinforcements of at least one coolant volume flow and / or one

Vehicle speed and / or an outside temperature are dependent.

8. The method according to claim 7, characterized in that the controller gains are determined by an observer.

9. The method according to claim 6, characterized in that the setpoint for the cooling reserve differential temperature is taken from a map that at least from the operating state of the internal combustion engine, in particular an engine load, and / or from the driver type and / or from a driving situation and / or from a cooling circuit state is dependent.

10. The method according to any one of the preceding claims, characterized in that the control is carried out in such a way that an operating point-dependent minimum volume flow of a coolant is ensured.

11. The method according to any one of the preceding claims, characterized in that a radiator fan and a radiator blind are controlled by the control as a common component.

12. Computer program for an internal combustion engine of a motor vehicle, with a sequence of commands which are suitable for carrying out the method according to one of claims 1 to 11 when they are executed on a computer, in particular a control device for an internal combustion engine.

13. The computer program according to claim 12, wherein the sequence of instructions is stored on a computer-readable data carrier.

14. Control device for controlling electrically actuatable components of a cooling system for an internal combustion engine of a motor vehicle, characterized in that the control device for controlling the components has at least one pilot control.

15. Cooling system for an internal combustion engine of a motor vehicle with controllable, electrically actuated components, the components being controlled by a control device, characterized in that the control device has at least one pilot control for controlling the components.

16. Internal combustion engine of a motor vehicle, in which electrically actuable components of a cooling system for the internal combustion engine can be controlled, the components being controlled by a control device, characterized in that the control device has at least one pilot control for controlling the components.