EP0640753B1 - Cooling system for an internal combustion engine - Google Patents

Cooling system for an internal combustion engine Download PDF

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Publication number
EP0640753B1
EP0640753B1 EP94108811A EP94108811A EP0640753B1 EP 0640753 B1 EP0640753 B1 EP 0640753B1 EP 94108811 A EP94108811 A EP 94108811A EP 94108811 A EP94108811 A EP 94108811A EP 0640753 B1 EP0640753 B1 EP 0640753B1
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EP
European Patent Office
Prior art keywords
temperature
expansion element
heating
combustion engine
internal combustion
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP94108811A
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German (de)
French (fr)
Other versions
EP0640753A1 (en
Inventor
Gerhart Huemer
Norbert Dembinski
Günter Ranzinger
Josef Krowiorz
Jochem Huber
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Bayerische Motoren Werke AG
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Bayerische Motoren Werke AG
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P7/00—Controlling of coolant flow
    • F01P7/14—Controlling of coolant flow the coolant being liquid
    • F01P7/16—Controlling of coolant flow the coolant being liquid by thermostatic control
    • F01P7/167—Controlling of coolant flow the coolant being liquid by thermostatic control by adjusting the pre-set temperature according to engine parameters, e.g. engine load, engine speed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P2025/00—Measuring
    • F01P2025/08—Temperature
    • F01P2025/13—Ambient temperature
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P2025/00—Measuring
    • F01P2025/08—Temperature
    • F01P2025/32—Engine outcoming fluid temperature
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P2025/00—Measuring
    • F01P2025/60—Operating parameters
    • F01P2025/62—Load
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P2025/00—Measuring
    • F01P2025/60—Operating parameters
    • F01P2025/64—Number of revolutions
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P2025/00—Measuring
    • F01P2025/60—Operating parameters
    • F01P2025/66—Vehicle speed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P2070/00—Details
    • F01P2070/04—Details using electrical heating elements

Definitions

  • the invention relates to a cooling system for an internal combustion engine a motor vehicle with a radiator and a Thermostatic valve with which the temperature of the coolant in a warm-up mode, a mixed mode and one Cooler operation is adjustable, the thermostatic valve contains an expansion element that is used to reduce the Coolant temperature is electrically heated.
  • the thermostatic valve regulates the flow of the coolant between the internal combustion engine and the radiator such that during the warm-up operation that of the internal combustion engine coming coolants essentially bypassing the cooler through a short circuit to Internal combustion engine flows back that during mixed operation the coolant coming from the internal combustion engine partly through the cooler and partly through flows back through the short circuit to the internal combustion engine and that during cooler operation that from Combustion coolant coming essentially flows back through the cooler to the internal combustion engine.
  • the electrical heating of the expansion element serves to enlarge the opening cross-section to the cooler towards one by the temperature of the coolant conditional opening cross section.
  • a cooling system for example from DE 30 18 682 A1.
  • the cooling system is in an expansion element an electric heating resistor of a thermostatic valve arranged, the electrical energy through a stationary held working piston can be fed through.
  • the feed the electrical energy takes place via a control device, the coolant temperature regulated by the thermostatic valve better than a normal thermostatic valve to be able to keep constant.
  • the Actual coolant temperature measured and with a predetermined upper and with a predetermined lower temperature value compared. If the upper temperature value is reached, so the heating resistor with electrical energy supplied so that the thermostatic valve opens further, to increase the cooling capacity and thus reduce the Actual coolant temperature can be reached.
  • the invention has for its object a cooling system of the type mentioned at the outset, as simple as possible, that the operation of the internal combustion engine with respect optimized fuel consumption and emissions can be without in the event of an increased power requirement the performance of the internal combustion engine is reduced is.
  • the expansion element is designed such that the coolant temperature (T K , T Kist ) adjusts to an upper working limit temperature (T AG ) without heating the expansion element in mixed operation, and in that a control unit (18) is provided, which, depending on the detected operating and / or environmental variables (DK, n, v, T S , LAST, T Kist , LL) of the internal combustion engine (10) releases the heating of the expansion element if necessary in order to operate the Relocate cooling system to cooler operation.
  • a control unit (18) is provided, which, depending on the detected operating and / or environmental variables (DK, n, v, T S , LAST, T Kist , LL) of the internal combustion engine (10) releases the heating of the expansion element if necessary in order to operate the Relocate cooling system to cooler operation.
  • the upper working limit temperature is preferably the same the most economical operating temperature of the internal combustion engine and is slightly smaller than the maximum permissible operating temperature of the internal combustion engine.
  • the upper working limit temperature is preferably above 100 ° C, especially at approx. 105 ° C.
  • the maximum allowable Operating temperature is the highest possible temperature with which the internal combustion engine in normal operation for longer Time can be operated without problems. Thereby even if the electrical heating of the Expansion element damage to the internal combustion engine prevented.
  • the maximum permissible is usually Operating temperature between 105 ° C and 120 ° C.
  • expansion element If the expansion element is not heated electrically, there is only one opening cross-section to the radiator depending on the coolant temperature a. This cross-section of the opening regulates the Coolant temperature to the defined upper working limit temperature.
  • Expansion element e.g. by selecting an appropriate one temperature-dependent material and a suitable con. structural design, designed so that at the defined upper working limit of the opening cross section the cooler is not yet maximum, d. H. no pure cooler operation is achieved. So through additional heating of the expansion element another Enlargement of the opening cross-section and thus one Relocation in the direction of the cooler operation possible.
  • the highest possible operating temperature of the internal combustion engine reached is for example due to less friction the power consumption of the internal combustion engine less, whereby lower fuel consumption and exhaust gas composition can improve.
  • a lower coolant temperature level requires quickly to this coolant temperature level being able to switch over depends on the operating and / or environmental variables electrical energy the heatable Expansion element supplied in the sense that increased cooling capacity by opening the thermostatic valve is obtained and thus a reduced Coolant temperature is reached quickly. Too high coolant or engine temperatures with increased performance requirements would result in a reduced degree of filling and thus lead to reduced performance.
  • the controller preferably locks the heating or the supply of electrical Energy to the expansion element when the sensed Actual temperature of the coolant below a predetermined Target temperature is.
  • the specified target temperature is always below the defined upper one Working limit temperature. This ensures that a control of the coolant temperature in the direction of a reduced temperature levels is only made if a minimum temperature has already been reached.
  • control system releases or blocks the heating of the expansion element depending on the vehicle speed.
  • idling can be determined when the motor vehicle is at a standstill, whereupon cooling may become necessary due to the lack of a headwind and thus the heating of the expansion element is released.
  • the controller releases or blocks the heating of the expansion element depending on the speed of the internal combustion engine, the throttle valve opening angle and / or the load state of the internal combustion engine.
  • the control unit (18) can compare the actual load state (LAST) and / or the actual throttle valve opening angle (DK) and / or the actual speed (n) with a predetermined threshold value and release the heating of the expansion element if this threshold value is exceeded.
  • the load state of the internal combustion engine can be determined, for example, by the speed of the internal combustion engine in connection with the opening angle of the throttle valve without height correction or in connection with the air mass in the intake tract with height correction.
  • a target temperature of the coolant as a function of the throttle valve angle and the rotational speed can also be determined in the form of a map.
  • the control gives the heating of the expansion element free if the actual temperature of the intake air or the Ambient temperature above a specified value lies. This ensures that at high outside temperatures for example when driving slowly, when idling one at a standstill or during stop-and-go operation Overheating of the internal combustion engine is prevented.
  • the target temperature of the coolant is indicated by a or several tables, characteristic curves and / or maps depending taken from several company and environmental variables. For example, to create a Coolant temperature map of a variety of operating points, e.g. by the values of the speed of the Internal combustion engine, the throttle valve opening angle and / or the vehicle speed are defined, individual Assigned coolant temperatures. The feed the electrical energy to the expansion element is released, if the target temperature taken from the map below the current actual temperature of the coolant lies. With this training it is possible to Coolant temperature at every operating point or operating state to optimize the internal combustion engine.
  • control unit heats the expansion element only after a given company size or environmental size hysteresis and / or according to a predetermined one Delay time releases when the heating of the Expanding element releasing condition is met.
  • control unit heats the expansion element only after a specified company size or environmental variable hysteresis and / or according to a predetermined Delay time locks when the heating of the expansion element blocking condition is met. For example, at a target temperature above the actual temperature is the supply of electrical energy to the expansion element only after a predetermined temperature hysteresis and / or after a predetermined delay time blocked.
  • a further advantageous embodiment of the invention exists according to the subject matter of claim 6 in that the each predetermined target temperature essentially by one depending on the company and / or environmental parameters permissible maximum temperature of the coolant is determined becomes.
  • the intention of this embodiment according to the invention is that to optimize fuel consumption and the highest possible exhaust gas emissions Operating temperature of the internal combustion engine set which, however, depends on the current load of the internal combustion engine is determined only so high that damage to the internal combustion engine or loss of performance is avoided due to overheating.
  • releasing the feed electrical energy or heating is not mandatory an actual switching on of the energy supply for Consequence.
  • a release can only be one on one certain condition-based switch-on option.
  • Actual switch-on can be, for example, from a logical combination of several by different Operating and environmental parameters caused switch-on options depend.
  • the term blocking can also be used as a blocking option based on an individual condition or as actual switching off can be understood.
  • the cooling system shown in Fig. 1 for an internal combustion engine 10 contains a radiator 11. Between the internal combustion engine 10 and the radiator 11 is a coolant pump 12 attached that a flow of the coolant in generates the direction shown by arrows. From the coolant outlet of the internal combustion engine 10 leads a flow line 13 to the coolant inlet of the radiator 11. From Coolant outlet of the cooler 11 leads to the coolant inlet of the internal combustion engine 10 a return line 14. In the return line 14 is a thermostatic valve 15 with an expansion element, not shown here arranged. One branches off from the supply line 13 Short circuit line 16 to the thermostatic valve 15.
  • the cooling system essentially works in three operating modes.
  • a first mode of operation the so-called warm-up mode especially after the cold start of the internal combustion engine 10
  • the thermostatic valve 15 is set so that coming from the engine 10 Coolant flow over the short-circuit line 16 essentially completely returned to the internal combustion engine 10 becomes.
  • the Cooling system in mixed operation, d. H. that of the internal combustion engine 10 coming coolant partially runs through the radiator 11 and partly back via the short-circuit line 16 to the internal combustion engine 10.
  • the cooling system works in cooler mode, d. H. that from Internal combustion engine 10 will essentially coolant completely through the cooler 11 to Internal combustion engine 10 returned.
  • the cooling system can be operated by heating the Expansion element of the thermostatic valve 15 via a electrical line 17 in the direction of cooling operation adjusted or switched completely to cooler operation will. This reduces the temperature level of the Coolant compared to that with an operation without Heating of the expansion element reached the temperature level. Then the heating is done via the electrical line 17 interrupted again, so the cooler now Coolant the expansion element of the thermostatic valve 15 from until it reaches a regulated end position in mixed operation occupies so that the coolant temperature back to a Final temperature is raised.
  • the regulated final temperature in mixed operation according to the invention on the upper Working limit temperature set.
  • the supply of the thermostatic valve 15 with electrical Energy via line 17 is supplied by a control unit 18 causes several signals of company and / or environmental variables receives and evaluates.
  • a temperature sensor 19 arranged, which detects the actual temperature of the coolant and transmitted to the control unit 18.
  • the intake pipe of the internal combustion engine 10 is another Temperature sensor 20 arranged, the temperature the intake air (fresh air) detected and to the Control device 18 passes on.
  • the Control device 18 in a known electronic Motor control 21 integrated, for example to a the "Motronic" trademark from Robert Bosch GmbH distributed electronic engine control.
  • the motor controller 21 provides signals for the detection of Operating and environmental parameters, such as vehicle speed, the ambient temperature, the speed of the Internal combustion engine and / or the throttle valve opening angle, to disposal. Furthermore, the Engine control 21 the load state of the internal combustion engine 10 from the detected signals. The load state is, for example directly or indirectly from the position of Throttle valve, from the speed and / or the air mass in Intake pipe determined. Depending on the control unit 18 obtained signals is, for example, a target temperature of the coolant determined. If this target temperature is lower than the actual temperature of the coolant, the expansion element of the thermostatic valve 15 over the line 17 heated.
  • Operating and environmental parameters such as vehicle speed, the ambient temperature, the speed of the Internal combustion engine and / or the throttle valve opening angle
  • Coolant temperature control shown where the heating is actually switched on of the expansion element ("heat expansion element") via a particularly advantageous logical link several individual conditions related to different Operating and environmental variables of the motor vehicle controlled becomes.
  • control logic is for example in the Control unit 18 is stored, the control unit 18 for example in an already existing control unit integrated or a separate integrated component in the Thermostatic valve itself can be.
  • the operating and environmental variables throttle valve opening angle DK, engine speed n, actual temperature of the coolant T Kist , vehicle speed v and intake air temperature T S which are present, for example, in the form of sensor signals, are processed to control the coolant temperature.
  • status signals which were formed from a combination of the individual sensor signals or the operating and environmental variables can also be processed in the control system.
  • a status signal is the idle signal LL when the vehicle is at a standstill, this signal being formed, for example, from the vehicle speed v and the engine speed n.
  • the sensor signals throttle valve opening angle DK and engine speed n are used to determine the setpoint temperature T Ksoll of the coolant from a characteristic map K at the operating points determined by the throttle valve opening angle DK and the engine speed n.
  • the target temperature of the coolant T Ksoll determined in this way is compared with the actual temperature of the coolant T Kist . If the actual temperature T Kist is greater than the target temperature T Ksoll , the heating of the expansion element is released.
  • a release corresponds to a release option F (circled), not necessarily an actual heating.
  • a hysteresis element VT it is observed in a hysteresis element VT whether the difference ⁇ T between the actual and target temperature changes by more than a predetermined difference ⁇ T H. Only then is the release option F for heating the expansion element maintained. For this purpose, a logic high signal is emitted at the output of the hysteresis element VT. This output signal of the hysteresis element VT is fed to the inputs of the AND gates AND-1 and AND-3.
  • a logic corresponds in general High signal of a release option F.
  • Further release options F for switching on the heating of the expansion element are generated as a function of the intake air temperature T S.
  • the heating of the expansion element depending on the intake air temperature T S should only be released if at least one of the three thresholds TS1, TS2 and TS3 is exceeded.
  • a logic high signal is sent to the AND gate AND-1
  • a logic high signal is sent to the AND gate UND-2
  • a logic high signal is sent to the AND gate UND-2
  • the third threshold TS3 is exceeded a logic signal High signal sent to the AND gate UND-3.
  • the release option F for heating the expansion element can also depend on a vehicle speed threshold VS of the vehicle speed v being exceeded, whereupon a logic high signal is output from the output of a further hysteresis element VV to a second input of the AND gate UND-2.
  • a logic high signal is output from the output of a further hysteresis element VV to a second input of the AND gate UND-2.
  • the hysteresis elements VT and VV can also be time delay elements be or connected with time delay elements will.
  • the outputs of the AND gates UND-1 to AND-3 are three Inputs of an OR gate OR connected. If on the Output line of at least one AND gate a logic High signal is also present at the output of the OR gate a release option F in the form of a logical high signal generated.
  • a time delay element ⁇ t on Output of the OR gate can be provided through the one Release option F at the output of the OR gate only then actual heating of the expansion element leads, if this release option F is present for a predetermined time ⁇ t, in order to keep a constant and to prevent the heating from being switched off.
  • the vehicle speed threshold VS is preferably a vehicle speed v at which the internal combustion engine is subjected to high thermal loads.
  • the thresholds TS1 to TS3 of the intake air temperature T S are coordinated, for example, depending on the country version of the vehicle or the type of combustion engine or cooler.
  • the threshold TS3 will, for example, be lower than the thresholds TS1 and TS2, since in connection with the idling of the engine, in which no additional cooling occurs due to the wind, more cooling is required than, for example, at high vehicle speeds. Therefore, for example, the threshold TS2, which is designed in conjunction with the vehicle speed threshold VS, will be higher than the thresholds TS1 and TS3, since additional cooling occurs due to the wind at higher vehicle speeds.
  • vehicle and intake air temperature thresholds will be empirically determined in trials. It is important, for example, in very cold ambient or intake air temperatures (for example in “northern countries”) to control the cooler operation as a function of the intake or ambient temperature in order to counter thermal shock of the internal combustion engine. At. very hot ambient or intake air temperatures (eg in "tropical countries”) can regulate the coolant temperature depending on the intake or ambient temperature, a weakness in hot idling or Stop-and-go operations can be avoided.
  • the invention also at one to one Release option F leading fulfillment of only one of the in Fig. 2 conditions actually heating can be switched on. That is, for example the points marked with circled F in FIG. 2 each one directly with the switch-on device the heating of the expansion element can be connected.
  • FIG. 3 shows a diagram of the course of the coolant temperature T K over time t at part load and full load, as can be achieved by means of the cooling system according to the invention.
  • the expansion element of the thermostatic valve 15 is designed, for example, by the composition of the expansion material to an upper working limit temperature T AG , which here is a coolant temperature of approximately 105 ° C. in the regulated mixed operation. This temperature is shown with an upper line.
  • T AG which here is a coolant temperature of approximately 105 ° C. in the regulated mixed operation. This temperature is shown with an upper line.
  • a temperature level of 105 ° C in the partial load range is expedient in order to reduce fuel consumption by reducing friction or the like and at the same time to improve the exhaust gas composition.
  • the coolant temperature should always be as hot as possible to optimize consumption, but should be cool to improve the filling in the case of performance requirements in the full-load range.
  • the coolant temperature T K is brought to the temperature level of 105 ° C with a higher temperature gradient dT / dt than is possible with other cooling systems in warm-up mode and then in mixed mode during part-load operation.
  • the expansion element of the thermostatic valve 15 is heated exclusively by the coolant temperature T K.
  • the expansion element is designed so that at 105 ° C here the possible adjustment path of the valve or the maximum possible opening cross section has not yet been set.
  • the expansion element can be heated so strongly, for example, that a maximum opening cross-section to the cooler is set in order to cool down as quickly as possible, thereby completely switching to cooler operation.
  • a temperature level of approx. 70 ° C is reached after a short cooling time. If the operation of the internal combustion engine 10 goes from full load at point E back to partial load, the supply of electrical energy to the expansion element is interrupted.
  • the now cooler coolant which flows around the expansion element, cools the expansion material and causes the thermostatic valve to be adjusted again by the expansion element solely as a function of the coolant temperature T K.
  • the thermostatic valve then regulates the coolant temperature T K and thus the temperature of the internal combustion engine 10 to the temperature level of 105 ° C.
  • Cooling the coolant temperature T K in full-load operation to, for example, a temperature level of approximately 70 ° C. has the advantage that the internal combustion engine 10 can then provide the full power. It is thus avoided that, due to an excessively high temperature, a lower degree of filling during combustion is obtained, which leads to a reduction in performance.
  • the regulated lowering of the coolant temperature T K by heating the expansion element can also be regulated depending on various other operating and / or environmental variables of the motor vehicle.
  • Full load can be recognized, for example, by variables such as the vehicle speed, the engine speed or the throttle valve angle. For example, it is also sensible to lower the coolant temperature T K by heating the expansion element at very low vehicle speeds or when the vehicle is idling and at a standstill as well as at high outside temperatures, when driving uphill or in trailer operation.
  • the load state LAST can in turn be determined, for example, as a function of the throttle valve opening angle and the speed or the air mass in the intake pipe.
  • the one determined by two company sizes Setpoint temperature of the coolant assigned to the operating point can be calculated or empirically determined by experiment will. It is also possible to set a target temperature of the Coolant depending on several maps determine the different farm and / or environmental sizes process the vehicle.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
  • Air-Conditioning For Vehicles (AREA)

Description

Die Erfindung betrifft eine Kühlanlage für einen Verbrennungsmotor eines Kraftfahrzeuges mit einem Kühler und einem Thermostatventil, mit dem die Temperatur des Kühlmittels in einem Warmlaufbetrieb, einem Mischbetrieb und einem Kühlerbetrieb regelbar ist, wobei das Thermostatventil ein Dehnstoffelement enthält, das zum Reduzieren der Kühlmitteltemperatur elektrisch beheizbar ist.The invention relates to a cooling system for an internal combustion engine a motor vehicle with a radiator and a Thermostatic valve with which the temperature of the coolant in a warm-up mode, a mixed mode and one Cooler operation is adjustable, the thermostatic valve contains an expansion element that is used to reduce the Coolant temperature is electrically heated.

Dabei regelt das Thermostatventil die Strömung des Kühlmittels zwischen dem Verbrennungsmotor und dem Kühler derart, daß während des Warmlaufbetriebs das vom Verbrennungsmotor kommende Kühlmittel im wesentlichen unter Umgehen des Kühlers durch einen Kurzschluß hindurch zum Verbrennungsmotor zurückströmt, daß während des Mischbetriebs das von dem Verbrennungsmotor kommende Kühlmittel teilweise durch den Kühler hindurch und teilweise durch den Kurzschluß hindurch zum Verbrennungsmotor zurückströmt und daß während des Kühlerbetriebs das vom Verbrennungsmotor kommende Kühlmittel im wesentlichen durch den Kühler hindurch zum Verbrennungsmotor zurückströmt. Die elektrische Beheizung des Dehnstoffelements dient zum Vergrößern des Öffnungsquerschnittes zum Kühler hin gegenüber einem durch die Temperatur des Kühlmittels bedingten Öffnungsquerschnitt. The thermostatic valve regulates the flow of the coolant between the internal combustion engine and the radiator such that during the warm-up operation that of the internal combustion engine coming coolants essentially bypassing the cooler through a short circuit to Internal combustion engine flows back that during mixed operation the coolant coming from the internal combustion engine partly through the cooler and partly through flows back through the short circuit to the internal combustion engine and that during cooler operation that from Combustion coolant coming essentially flows back through the cooler to the internal combustion engine. The electrical heating of the expansion element serves to enlarge the opening cross-section to the cooler towards one by the temperature of the coolant conditional opening cross section.

Eine Kühlanlage nach dem Oberbegriff des Patentanspruchs 1 ist beispielsweise aus der DE 30 18 682 A1 bekannt. Bei dieser bekannten Kühlanlage ist in einem Dehnstoffelement eines Thermostatventils ein elektrischer Heizwiderstand angeordnet, dem elektrische Energie durch einen stationär gehaltenen Arbeitskolben hindurch zuführbar ist. Die Zufuhr der elektrischen Energie erfolgt über eine Regeleinrichtung, um die vom Thermostatventil eingeregelte Kühlmitteltemperatur besser als bei einem normalen Thermostatventil konstant halten zu können. Hierzu wird die Ist-Kühlmitteltemperatur gemessen und mit einem vorgegebenen oberen und mit einem vorgegebenen unteren Temperaturwert verglichen. Wird der obere Temperaturwert erreicht, so wird der Heizwiderstand mit elektrischer Energie versorgt, so daß das Thermostatventil weiter öffnet, um eine erhöhte Kühlleistung und damit eine Absenkung der Ist-Kühlmitteltemperatur zu erreichen. Sinkt die Ist-Kühlmitteltemperatur danach unter den unteren Temperaturwert, so wird die Zufuhr von elektrischer Energie zu dem Heizwiderstand unterbrochen, so daß das Dehnstoffelement vom kälteren Kühlmittel abgekühlt wird. Dadurch wird der Ventilquerschnitt wieder verringert, so daß die Ist-Kühlmitteltemperatur wieder ansteigt. Diese Regelspiele werden ständig wiederholt, um eine Kühlmitteltemperatur von beispielsweise 95°C möglichst konstant einzuhalten.A cooling system according to the preamble of the claim 1 is known for example from DE 30 18 682 A1. At this known cooling system is in an expansion element an electric heating resistor of a thermostatic valve arranged, the electrical energy through a stationary held working piston can be fed through. The feed the electrical energy takes place via a control device, the coolant temperature regulated by the thermostatic valve better than a normal thermostatic valve to be able to keep constant. For this, the Actual coolant temperature measured and with a predetermined upper and with a predetermined lower temperature value compared. If the upper temperature value is reached, so the heating resistor with electrical energy supplied so that the thermostatic valve opens further, to increase the cooling capacity and thus reduce the Actual coolant temperature can be reached. The actual coolant temperature drops then below the lower temperature value, so the supply of electrical energy to that Heating resistor interrupted so that the expansion element is cooled by the colder coolant. This will make the Valve cross section reduced again, so that the actual coolant temperature rises again. These rules games will be constantly repeated to a coolant temperature of for example, to keep 95 ° C as constant as possible.

Auch aus der US 4,666,081 ist eine Temperaturregeleinrichtung für eine Kühlanlage einer Brennkraftmaschine bekannt, durch die mittels eines Thermostats grundsätzlich die Kühlmitteltemperatur auf einen vorgegebenen Normalwert eingeregelt wird. Während des Warmlaufs der Brennkraftmaschine wird die Kühlmitteltemperatur erhöht, bei extremer Belastung der Brennkraftmaschine wird die Kühlmitteltemperatur reduziert. Gerade bei erhöhter Lastanforderung der Brennkraftmaschine wirkt sich eine Reduzierung der Kühlmitteltemperatur leistungsverringernd auf die Brennkraftmaschine aus.From US 4,666,081 is a temperature control device for a Cooling system of an internal combustion engine known, by means of a Thermostats basically set the coolant temperature to a predetermined one Normal value is adjusted. During the warm-up of the internal combustion engine the coolant temperature is increased under extreme loads Internal combustion engine, the coolant temperature is reduced. Especially with increased A load reduction of the internal combustion engine has an effect the coolant temperature reducing performance on the internal combustion engine out.

Aus dem Patent abstract of Japan, Nr. 454 (M-769) (JP 63183216), ist ebenfalls eine Temperaturregeleinrichtung für Kühlanlagen einer Brennkraftmaschine bekannt, durch die mittels eines elektrisch beheizbaren Dehnstoffelementes die Kühlmitteltemperatur in Abhängigkeit von der Außentemperatur eingestellt wird. Eine weitergehende Regelstrategie ist aus dieser Druckschrift nicht zu entnehmen.From patent abstract of Japan, No. 454 (M-769) (JP 63183216) also a temperature control device for cooling systems of an internal combustion engine known, by means of an electrically heated Expansion element, the coolant temperature depending on the outside temperature is set. A further control strategy is over not to be inferred from this publication.

Aus der DE 37 05 232 A1 ist eine Temperaturregeleinrichtung bekannt, bei der anstelle eines üblichen Thermostatventils mit einem Dehnstoffelement ein mittels eines Stellmotors regelbares Ventil vorgesehen ist. Bei dieser bekannten Temperaturregeleinrichtung wird der Stellmotor zur Verstellung des Ventils in Abhängigkeit von einem Sensor gesteuert, der die Kühlmitteltemperatur in einer mit dem Verbrennungsmotor verbundenen Leitung mißt. Der Sensor ist darüber hinaus mit einer Heizeinrichtung versehen. Die Heizeinrichtung ist in Abhängigkeit von Kennfeldgrößen des Verbrennungsmotors ein- und ausschaltbar. Bei dieser bekannten Temperaturregeleinrichtung kann demnach durch Beheizen des Sensors eine höhere als die reale Kühlmitteltemperatur vorgetäuscht werden, um eine verstärkte Kühlung des Kühlmittels zu erzeugen. Eine derartige Temperaturregeleinrichtung ist konstruktiv besonders aufwendig und damit konstenintensiv.DE 37 05 232 A1 describes a temperature control device known in the place of a conventional thermostatic valve with an expansion element by means of a Servomotor adjustable valve is provided. At this Known temperature control device is the servomotor to adjust the valve depending on one Sensor controlled that the coolant temperature in a line connected to the internal combustion engine. Of the The sensor is also equipped with a heating device. The heating device is dependent on map sizes of the internal combustion engine can be switched on and off. In this known temperature control device can accordingly by heating the sensor higher than the real one Coolant temperature can be faked to an increased To generate cooling of the coolant. Such Temperature control device is constructively special complex and therefore costly.

Der Erfindung liegt die Aufgabe zugrunde, eine Kühlanlage der eingangs genannten Art möglichst einfach so weiterzubilden, daß damit der Betrieb des Verbrennungsmotors bezüglich des Kraftstoffverbrauchs und der Abgaswerte optimiert werden kann, ohne daß im Falle eines erhöhten Leistungsbedarfs die Leistung des Verbrennungsmotors verringert ist.The invention has for its object a cooling system of the type mentioned at the outset, as simple as possible, that the operation of the internal combustion engine with respect optimized fuel consumption and emissions can be without in the event of an increased power requirement the performance of the internal combustion engine is reduced is.

Diese Aufgabe wird nach dem Kennzeichenteil des Anspruchs 1 dadurch gelöst, daß das Dehnstoffelement derart ausgelegt wird, daß sich die Kühlmitteltemperatur (TK, TKist) ohne Beheizung des Dehnstoffelementes im Mischbetrieb auf eine obere Arbeitsgrenztemperatur (TAG) einregelt, und daß eine Steuereinheit (18) vorgesehen ist, die abhängig von erfaßten Betriebs- und/oder Umweltgrößen (DK, n, v, TS, LAST, TKist, LL) des Verbrennungsmotors (10) die Beheizung des Dehnstoffelementes bei Bedarf freigibt, um die Betriebsweise der Kühlanlage hin zum Kühlerbetrieb zu verlagern.This object is achieved according to the characterizing part of claim 1 in that the expansion element is designed such that the coolant temperature (T K , T Kist ) adjusts to an upper working limit temperature (T AG ) without heating the expansion element in mixed operation, and in that a control unit (18) is provided, which, depending on the detected operating and / or environmental variables (DK, n, v, T S , LAST, T Kist , LL) of the internal combustion engine (10) releases the heating of the expansion element if necessary in order to operate the Relocate cooling system to cooler operation.

Die obere Arbeitsgrenztemperatur ist vorzugsweise gleich der verbrauchsgünstigsten Betriebstemperatur des Verbrennungsmotors und ist geringfügig kleiner als die maximal zulässige Betriebstemperatur des Verbrennungsmotors. Vorzugsweise liegt die obere Arbeitsgrenztemperatur über 100°C, insbesondere bei ca. 105°C. Die maximal zulässige Betriebstemperatur ist die höchst mögliche Temperatur, mit der der Verbrennungsmotor im Normalbetrieb über längere Zeit störungsfrei betrieben werden kann. Dadurch wird auch bei Ausfall der elektrischen Beheizung des Dehnstoffelements eine Beschädigung des Verbrennungsmotors verhindert. Üblicherweise liegt die maximal zulässige Betriebtemperatur zwischen 105°C und 120°C.The upper working limit temperature is preferably the same the most economical operating temperature of the internal combustion engine and is slightly smaller than the maximum permissible operating temperature of the internal combustion engine. The upper working limit temperature is preferably above 100 ° C, especially at approx. 105 ° C. The maximum allowable Operating temperature is the highest possible temperature with which the internal combustion engine in normal operation for longer Time can be operated without problems. Thereby even if the electrical heating of the Expansion element damage to the internal combustion engine prevented. The maximum permissible is usually Operating temperature between 105 ° C and 120 ° C.

Wird das Dehnstoffelement nicht elektrisch beheizt, stellt sich ein Öffnungsquerschnitt zum Kühler hin ausschließlich in Abhängigkeit von der Kühlmitteltemperatur ein. Dieser Öffnungsquerschnitt bewirkt ein Einregeln der Kühlmitteltemperatur auf die definierte obere Arbeitsgrenztemperatur. Dabei wird erfindungsgemäß das Dehnstoffelement, z.B. durch Auswahl eines entsprechenden temperaturabhängigen Materials und einer geeigneten kon-. struktiven Ausgestaltung, so ausgelegt, daß bei der definierten oberen Arbeitsgrenztemperatur der Öffnungsquerschnitt des Kühlers noch nicht maximal ist, d. h. kein reiner Kühlerbetrieb erreicht wird. So ist durch zusätzliches Beheizen des Dehnstoffelements eine weitere Vergrößerung des Öffnungsquerschnittes und damit eine Verlagerung in Richtung des Kühlerbetriebes hin möglich.If the expansion element is not heated electrically, there is only one opening cross-section to the radiator depending on the coolant temperature a. This cross-section of the opening regulates the Coolant temperature to the defined upper working limit temperature. According to the invention Expansion element, e.g. by selecting an appropriate one temperature-dependent material and a suitable con. structural design, designed so that at the defined upper working limit of the opening cross section the cooler is not yet maximum, d. H. no pure cooler operation is achieved. So through additional heating of the expansion element another Enlargement of the opening cross-section and thus one Relocation in the direction of the cooler operation possible.

Ergänzend sei darauf hingewiesen, daß der Öffnungsquerschnitt zum Kühler hin und der Öffnungsquerschnitt zu dem den Kühler umgehenden Kurzschluß hin gegensinnig verändert werden.In addition, it should be noted that the opening cross section to the radiator and the opening cross section to the the cooler immediate short circuit changed in opposite directions will.

Durch die Erfindung wird im Normalbetrieb, d.h. nicht bei erhöhter Leistungsanforderung wie z.B. im Vollastbetrieb oder bei Bergfahrt, eine möglichst hohe Betriebstemperatur des Verbrennungsmotors erreicht. Dabei ist beispielsweise aufgrund von geringerer Reibung die Leistungsaufnahme des Verbrennungsmotors geringer, wodurch sich der Kraftstoffverbrauch senken und die Abgaszusammensetzung verbessern läßt. Um jedoch dann, wenn der Betriebszustand des Verbrennungsmotors durch erhöhte Leistungsanforderung ein niedrigeres Kühlmitteltemperaturniveau erfordert, schnell auf dieses Kühlmitteltemperaturniveau umschalten zu können, wird abhängig von den Betriebs- und/oder Umweltgrößen elektrische Energie dem beheizbaren Dehnstoffelement in dem Sinne zugeführt, daß eine erhöhte Kühlleistung durch weiteres Öffnen des Thermostatventils erhalten wird und damit eine verringerte Kühlmitteltemperatur schnell erreicht wird. Zu hohe Kühlmittel- bzw. Motortemperaturen bei erhöhter Leistungsanforderung würden zu einem verringerten Füllungsgrad und damit zu einer verringerten Leistung führen.By the invention in normal operation, i.e. not at increased performance requirements such as in full load operation or when driving uphill, the highest possible operating temperature of the internal combustion engine reached. Here is for example due to less friction the power consumption of the internal combustion engine less, whereby lower fuel consumption and exhaust gas composition can improve. However, when the operating status of the internal combustion engine due to increased performance requirements a lower coolant temperature level requires quickly to this coolant temperature level being able to switch over depends on the operating and / or environmental variables electrical energy the heatable Expansion element supplied in the sense that increased cooling capacity by opening the thermostatic valve is obtained and thus a reduced Coolant temperature is reached quickly. Too high coolant or engine temperatures with increased performance requirements would result in a reduced degree of filling and thus lead to reduced performance.

Vorteilhafte Weiterbildungen der Erfindung sind die Gegenstände der weiteren Patentansprüche.Advantageous developments of the invention are the subject of the further claims.

Die Steuerung sperrt vorzugsweise die Beheizung bzw. die Zufuhr von elektrischer Energie zum Dehnstoffelement, wenn die erfaßte Ist-Temperatur des Kühlmittels unterhalb einer vorgegebenen Soll-Temperatur liegt. Die vorgegebene Soll-Temperatur liegt dabei stets unterhalb der definierten oberen Arbeitsgrenztemperatur. Damit wird sichergestellt, daß eine Regelung der Kühlmitteltemperatur in Richtung eines verringerten Temperaturniveaus nur dann vorgenommen wird, wenn eine Mindesttemperatur bereits erreicht ist.The controller preferably locks the heating or the supply of electrical Energy to the expansion element when the sensed Actual temperature of the coolant below a predetermined Target temperature is. The specified target temperature is always below the defined upper one Working limit temperature. This ensures that a control of the coolant temperature in the direction of a reduced temperature levels is only made if a minimum temperature has already been reached.

Weiterhin nimmt die Steuerung ein Freigeben bzw. Sperren der Beheizung des Dehnstoffelements in Abhängigkeit von der Fahrzeuggeschwindigkeit vor.
Zum einen kann beispielsweise der Leerlauf bei Stillstand des Kraftfahrzeuges festgestellt werden, worauf eine Kühlung wegen des fehlenden Fahrtwinds notwendig werden kann und damit die Beheizung des Dehnstoffelementes freigegeben wird. Furthermore, the control system releases or blocks the heating of the expansion element depending on the vehicle speed.
On the one hand, for example, idling can be determined when the motor vehicle is at a standstill, whereupon cooling may become necessary due to the lack of a headwind and thus the heating of the expansion element is released.

Wird eine sehr hohe Fahrzeuggeschwindigkeit und z. B. auch zusätzlich ein großer Drosselklappenöffnungswinkel erfaßt, wird auf eine erhöhte Leistungsanforderung an den Verbrennungsmotor geschlossen, wodurch ebenfalls eine erhöhte Kühlung sinnvoll ist und damit die Beheizung des Dehnstoffelementes freigegeben werden kann.If a very high vehicle speed and z. B. also a large throttle valve opening angle recorded, is to an increased performance requirement on the Internal combustion engine closed, which also increases Cooling is sensible and thus the heating of the Expansion element can be released.

Die Steuerung nimmt ein Freigeben bzw. Sperren der Beheizung des Dehnstoffelementes in Abhängigkeit von der Drehzahl des Verbrennungsmotors, des Drosselklappenöffnungswinkels und/oder dem Lastzustand des Verbrennungsmotors vor.
Beispielsweise kann die Steuereinheit (18) den Ist-Lastzustand (LAST) und/oder den Ist-Drosselklappenöffnungswinkel (DK) und/oder die Ist-Drehzahl (n) mit einem vorgegebenen Schwellwert vergleichen und bei Überschreiten dieses Schwellwertes die Beheizung des Dehnstoffelements freigeben.
Der Lastzustand des Verbrennungsmotors kann beispielsweise durch die Drehzahl des Verbrennungsmotors in Verbindung mit dem Öffnungswinkel der Drosselklappe ohne Höhenkorrektur oder in Verbindung mit der Luftmasse im Ansaugtrakt mit Höhenkorrektur festgestellt werden.
Es kann jedoch auch in Form eines Kennfeldes eine Soll-Temperatur des Kühlmittels in Abhängigkeit von dem Drosselklappenwinkel und der Drehzahl bestimmt werden.
Auf diese Weise wird sichergestellt, daß bei hoher Last oder bei hoher Drehzhal oder bei großem Drosselklappenöffnungswinkel die geforderte Leistungsabgabe des Verbrennungsmotors nicht durch eine zu hohe Betriebstemperatur reduziert wird, die zu einem verschlechterten Füllungsgrad und damit zu einer verringerten Leistung führen könnte. The controller releases or blocks the heating of the expansion element depending on the speed of the internal combustion engine, the throttle valve opening angle and / or the load state of the internal combustion engine.
For example, the control unit (18) can compare the actual load state (LAST) and / or the actual throttle valve opening angle (DK) and / or the actual speed (n) with a predetermined threshold value and release the heating of the expansion element if this threshold value is exceeded.
The load state of the internal combustion engine can be determined, for example, by the speed of the internal combustion engine in connection with the opening angle of the throttle valve without height correction or in connection with the air mass in the intake tract with height correction.
However, a target temperature of the coolant as a function of the throttle valve angle and the rotational speed can also be determined in the form of a map.
In this way it is ensured that at high load or at high speed or with a large throttle valve opening angle, the required power output of the internal combustion engine is not reduced by an excessively high operating temperature, which could lead to a deteriorated degree of filling and thus to a reduced output.

Die Steuerung gibt die Beheizung des Dehnstoffelementes frei , wenn die Ist-Temperatur der Ansaugluft oder der Umgebungstemperatur oberhalb eines vorgegebenen Wertes liegt. Damit wird sichergestellt, daß bei hohen Außentemperaturen beispielsweise bei langsamer Fahrt, bei Leerlauf im Stillstand oder bei Stop-and-go-Betrieb eine Überhitzung des Verbrennungsmotors verhindert wird.The control gives the heating of the expansion element free if the actual temperature of the intake air or the Ambient temperature above a specified value lies. This ensures that at high outside temperatures for example when driving slowly, when idling one at a standstill or during stop-and-go operation Overheating of the internal combustion engine is prevented.

Die Soll-Terperatur des Kühlmittels wird durch ein oder mehrere Tabellen, Kennlinien und/oder Kennfelder in Abhängigkeit von mehreren Betriebs- und Umweltgrößen entnommen. Beispielsweise werden zur Erstellung eines Kühlmitteltemperatur-Kennfeldes einer Vielzahl von Betriebspunkten, die z.B. durch die Werte der Drehzahl des Verbrennungsmotors, des Drosselklappenöffnungswinkels und/oder der Fahrzeuggeschwindigkeit definiert sind, einzelne Kühlmittel-Soll-Temperaturen zugeordnet. Die Zufuhr der elektrischen Energie zum Dehnstoffelement wird freigegeben, wenn die aus dem Kennfeld entnommene Soll-Temperatur unterhalb der momentanen Ist-Temperatur des Kühlmittels liegt. Mit dieser Ausbildung ist es möglich, die Kühlmitteltemperatur zu jedem Betriebspunkt oder Betriebszustand des Verbrennungsmotors zu optimieren.The target temperature of the coolant is indicated by a or several tables, characteristic curves and / or maps depending taken from several company and environmental variables. For example, to create a Coolant temperature map of a variety of operating points, e.g. by the values of the speed of the Internal combustion engine, the throttle valve opening angle and / or the vehicle speed are defined, individual Assigned coolant temperatures. The feed the electrical energy to the expansion element is released, if the target temperature taken from the map below the current actual temperature of the coolant lies. With this training it is possible to Coolant temperature at every operating point or operating state to optimize the internal combustion engine.

Eine weitere vorteilhafte Ausgestaltung der Erfindung ist der Gegenstand des Anspruchs 4. Darin wird vorgesehen, daß die Steuereinheit die Beheizung des Dehnstoffelementes erst nach einer vorgegebenen Betriebsgrößen- oder Umweltgrößen-Hysterese und/oder nach einer vorgegebenen Verzögerungszeit freigibt, wenn eine die Beheizung des Dehnstoffelementes freigebende Bedingung erfüllt ist. Another advantageous embodiment of the invention is the subject of claim 4. It provides that the control unit heats the expansion element only after a given company size or environmental size hysteresis and / or according to a predetermined one Delay time releases when the heating of the Expanding element releasing condition is met.

Beispielsweise wird bei einer Soll-Temperatur unterhalb der Ist-Temperatur die Beheizung des Dehnstoffelementes erst nach einer vorgegebenen Temperatur-Hysterese und/oder nach einer vorgegebenen Verzögerungszeit freigegeben.For example, at a target temperature below the actual temperature of the heating of the expansion element only after a specified temperature hysteresis and / or released after a predetermined delay time.

Ebenso ist nach dem Gegenstand des Anspruchs 5 vorgesehen, daß die Steuereinheit die Beheizung des Dehnstoffelementes erst nach einer vorgegebenen Betriebsgrößen- oder Umweltgrößen-Hysterese und/oder nach einer vorgegebenen Verzögerungszeit sperrt, wenn eine die Beheizung des Dehnstoffelementes sperrende Bedingung erfüllt ist. Beispielsweise wird bei einer Soll-Temperatur oberhalb der Ist-Temperatur die Zufuhr der elektrischen Energie zum Dehnstoffelement erst nach einer vorgegebenen Temperatur-Hysterese und/oder nach einer vorgegebenen Verzögerungszeit gesperrt.It is also provided according to the subject matter of claim 5 that the control unit heats the expansion element only after a specified company size or environmental variable hysteresis and / or according to a predetermined Delay time locks when the heating of the expansion element blocking condition is met. For example, at a target temperature above the actual temperature is the supply of electrical energy to the expansion element only after a predetermined temperature hysteresis and / or after a predetermined delay time blocked.

Mit diesen beiden Ausgestaltungen der Erfindung wird erreicht, daß bei nur kurzfristigen Änderungen der Betriebs- und/oder Umweltgrößen die Anzahl der Regelvor-. gänge reduziert wird. Das heißt, wenn von der Freigabe der Beheizung auf ein Sperren und umgekehrt übergegangen werden soll, wird dieser Übergang solange verzögert, bis eine längerfristige Änderung festgestellt wird.With these two configurations of the invention, that with only short-term changes in the operating and / or environmental variables the number of pre-rules. gears is reduced. That is, if from the release the heating switched to a lock and vice versa this transition is delayed until a longer-term change is found.

Eine weitere vorteilhafte Ausgestaltung der-Erfindung besteht nach dem Gegenstand des Anspruchs 6 darin, daß die jeweils vorgegebene Soll-Temperatur im wesentlichen durch eine in Abhängigkeit von den Betriebs- und/oder Umweltgrößen zulässige Maximaltemperatur des Kühlmittels bestimmt wird. Die Intention dieser erfindungsgemäßen Ausgestaltung ist, daß zur Optimierung des Kraftstoffverbrauchs und der Abgasemissionen eine höchstmögliche Betriebstemperatur des Verbrennungsmotors eingestellt wird, die jedoch abhängig von der momentanen Belastung des Verbrennungsmotors nur so hoch bestimmt wird, daß eine Beschädigung des Verbrennungsmotors oder ein Leistungsverlust aufgrund von Überhitzung vermieden wird.A further advantageous embodiment of the invention exists according to the subject matter of claim 6 in that the each predetermined target temperature essentially by one depending on the company and / or environmental parameters permissible maximum temperature of the coolant is determined becomes. The intention of this embodiment according to the invention is that to optimize fuel consumption and the highest possible exhaust gas emissions Operating temperature of the internal combustion engine set which, however, depends on the current load of the internal combustion engine is determined only so high that damage to the internal combustion engine or loss of performance is avoided due to overheating.

Es sei ergänzend angemerkt, daß ein Freigeben der Zufuhr der elektrischen Energie bzw. der Beheizung nicht zwingend ein tatsächliches Einschalten der Enegiezufuhr zur Folge hat. Eine Freigabe kann auch lediglich eine auf einer bestimmten Bedingung basierende Einschaltoption sein. Ein tatsächliches Einschalten kann beispielsweise von einer logischen Verknüpfung mehrerer durch unterschiedliche Betriebs- und Umweltgrößen hervorgerufenen Einschaltoptionen abhängen. Ebenso kann auch der Begriff Sperren als Sperroption bezogen auf eine Einzelbedingung oder als tatsächliches Ausschalten verstanden werden.It should also be noted that releasing the feed electrical energy or heating is not mandatory an actual switching on of the energy supply for Consequence. A release can only be one on one certain condition-based switch-on option. Actual switch-on can be, for example, from a logical combination of several by different Operating and environmental parameters caused switch-on options depend. The term blocking can also be used as a blocking option based on an individual condition or as actual switching off can be understood.

Die Erfindung wird anhand der nachfolgenden Beschreibung und der beigefügten Zeichnungen näher erläutert. Es zeigen

Fig. 1
ein Schemabild einer Kühlanlage, die der Erfindung zugrundeliegt
Fig. 2
einen Logikplan für eine mögliche erfindungsgemäße Regelung der Kühlanlage
Fig. 3
einen mit der erfindungsgemäßen Kühlanlage erreichbaren Temperaturverlauf der Kühlmitteltemperatur und
Fig. 4
die Darstellung eines Kühlmittel-Soll-Temperatur-Kennfeldes.
The invention is explained in more detail with reference to the following description and the accompanying drawings. Show it
Fig. 1
a schematic of a cooling system, which is the basis of the invention
Fig. 2
a logic plan for a possible control of the cooling system according to the invention
Fig. 3
a temperature profile of the coolant temperature that can be achieved with the cooling system according to the invention and
Fig. 4
the representation of a coolant target temperature map.

Die in Fig. 1 dargestellte Kühlanlage für einen Verbrennungsmotor 10 enthält einen Kühler 11. Zwischen dem Verbrennungsmotor 10 und dem Kühler 11 ist eine Kühlmittelpumpe 12 angebracht, die eine Strömung des Kühlmittels in die mit Pfeilen dargestellte Richtung erzeugt. Vom Kühlmittelaustritt des Verbrennungsmotors 10 führt eine Vorlaufleitung 13 zum Kühlmitteleingang des Kühlers 11. Vom Kühlmittelaustritt des Kühlers 11 führt zum Kühlmitteleintritt des Verbrennungsmotors 10 eine Rücklaufleitung 14. In der Rücklaufleitung 14 ist ein Thermostatventil 15 mit einem hier nicht dargestellten Dehnstoffelement angeordnet. Von der Vorlaufleitung 13 zweigt eine Kurzschlußleitung 16 zum Thermostatventil 15 ab.The cooling system shown in Fig. 1 for an internal combustion engine 10 contains a radiator 11. Between the internal combustion engine 10 and the radiator 11 is a coolant pump 12 attached that a flow of the coolant in generates the direction shown by arrows. From the coolant outlet of the internal combustion engine 10 leads a flow line 13 to the coolant inlet of the radiator 11. From Coolant outlet of the cooler 11 leads to the coolant inlet of the internal combustion engine 10 a return line 14. In the return line 14 is a thermostatic valve 15 with an expansion element, not shown here arranged. One branches off from the supply line 13 Short circuit line 16 to the thermostatic valve 15.

Die Kühlanlage arbeitet im wesentlichen in drei Betriebsweisen. In einer ersten Betriebsweise, dem sog. Warmlaufbetrieb insbesondere nach dem Kaltstart des Verbrennungsmotors 10, ist das Thermostatventil 15 so eingestellt, daß die vom Verbrennungsmotor 10 kommende Kühlmittelströmung über die Kurzschlußleitung 16 im wesentlichen vollständig zum Verbrennungsmotor 10 zurückgeführt wird. In einer zweiten Betriebsweise arbeitet die Kühlanlage im Mischbetrieb, d. h. das vom Verbrennungsmotor 10 kommende Kühlmittel läuft teilweise durch den Kühler 11 und teilweise über die Kurzschlußleitung 16 zurück zum Verbrennungsmotor 10. In einer dritten Betriebsweise arbeitet die Kühlanlage im Kühlerbetrieb, d. h. das vom Verbrennungsmotor 10 kommende Kühlmittel wird im wesentlichen vollständig durch den Kühler 11 hindurch zum Verbrennungsmotor 10 zurückgeführt.The cooling system essentially works in three operating modes. In a first mode of operation, the so-called warm-up mode especially after the cold start of the internal combustion engine 10, the thermostatic valve 15 is set so that coming from the engine 10 Coolant flow over the short-circuit line 16 essentially completely returned to the internal combustion engine 10 becomes. In a second mode of operation, the Cooling system in mixed operation, d. H. that of the internal combustion engine 10 coming coolant partially runs through the radiator 11 and partly back via the short-circuit line 16 to the internal combustion engine 10. In a third mode of operation the cooling system works in cooler mode, d. H. that from Internal combustion engine 10 will essentially coolant completely through the cooler 11 to Internal combustion engine 10 returned.

Die Betriebsweise der Kühlanlage kann durch Beheizung des Dehnstoffelementes des Thermostatventils 15 über eine elektrische Leitung 17 in Richtung des Kühlerbetriebes verstellt oder vollständig auf Kühlerbetrieb umgeschaltet werden. Damit verringert sich das Temperaturniveau des Kühlmittels gegenüber dem mit einer Betriebsweise ohne Beheizung des Dehnstoffelementes erreichten Temperaturniveau. Wird danach die Beheizung über die elektrische Leitung 17 wieder unterbrochen, so kühlt das jetzt kühlere Kühlmittel das Dehnstoffelement des Thermostatventils 15 ab bis es eine eingeregelte Endstellung im Mischbetrieb einnimmt, so daß die Kühlmitteltemperatur wieder auf eine Endtemperatur angehoben wird. Die eingeregelte Endtemperatur im Mischbetrieb wird erfindungsgemäß auf die obere Arbeitsgrenztemperatur festgelegt.The cooling system can be operated by heating the Expansion element of the thermostatic valve 15 via a electrical line 17 in the direction of cooling operation adjusted or switched completely to cooler operation will. This reduces the temperature level of the Coolant compared to that with an operation without Heating of the expansion element reached the temperature level. Then the heating is done via the electrical line 17 interrupted again, so the cooler now Coolant the expansion element of the thermostatic valve 15 from until it reaches a regulated end position in mixed operation occupies so that the coolant temperature back to a Final temperature is raised. The regulated final temperature in mixed operation according to the invention on the upper Working limit temperature set.

Die Versorgung des Thermostatventils 15 mit elektrischer Energie über die Leitung 17 wird von einem Steuergerät 18 veranlaßt, das mehrere Signale von Betriebs- und/oder Umweltgrößen erhält und auswertet. Am Kühlmittelaustritt des Verbrennungsmotors 10 ist ein Temperatursensor 19 angeordnet, der die Ist-Temperatur des Kühlmittels erfaßt und an das Steuergerät 18 übermittelt. In einem Sammler der Ansaugleitung des Verbrennungsmotors 10 ist ein weiterer Temperatursensor 20 angeordnet, der die Temperatur der Ansaugluft (Frischluft) erfaßt und an die Steuereinrichtung 18 weitergibt. Vorzugsweise ist die Steuereinrichtung 18 in einer bekannten elektronischen Motorsteuerung 21 integriert, beispielsweise an eine unter dem Warenzeichen "Motronic" von der Firma Robert Bosch GmbH vertriebene elektronische Motorsteuerung.The supply of the thermostatic valve 15 with electrical Energy via line 17 is supplied by a control unit 18 causes several signals of company and / or environmental variables receives and evaluates. At the coolant outlet of the internal combustion engine 10 is a temperature sensor 19 arranged, which detects the actual temperature of the coolant and transmitted to the control unit 18. In a collector the intake pipe of the internal combustion engine 10 is another Temperature sensor 20 arranged, the temperature the intake air (fresh air) detected and to the Control device 18 passes on. Preferably, the Control device 18 in a known electronic Motor control 21 integrated, for example to a the "Motronic" trademark from Robert Bosch GmbH distributed electronic engine control.

Die Motorsteuerung 21 stellt Signale zur Erfassung von Betriebs- und Umweltgrößen, wie der Fahrzeuggeschwindigkeit, der Umgebungstemperatur, der Drehzahl des Verbrennungsmotors und/oder den Drosselklappenöffnungswinkel, zur Verfügung. Ferner ermittelt die Motorsteuerung 21 den Lastzustand des Verbrennungsmotors 10 aus den erfaßten Signalen. Der Lastzustand wird beispielsweise direkt oder indirekt aus der Stellung der Drosselklappe, aus der Drehzahl und/oder der Luftmasse im Ansaugrohr bestimmt. Abhängig von den vom Steuergerät 18 erhaltenen Signalen wird beispielsweise eine Soll-Temperatur des Kühlmittels ermittelt. Wenn diese Soll-Temperatur kleiner als die Ist-Temperatur des Kühlmittels ist, wird das Dehnstoffelement des Thermostatventils 15 über die Leitung 17 beheizt.The motor controller 21 provides signals for the detection of Operating and environmental parameters, such as vehicle speed, the ambient temperature, the speed of the Internal combustion engine and / or the throttle valve opening angle, to disposal. Furthermore, the Engine control 21 the load state of the internal combustion engine 10 from the detected signals. The load state is, for example directly or indirectly from the position of Throttle valve, from the speed and / or the air mass in Intake pipe determined. Depending on the control unit 18 obtained signals is, for example, a target temperature of the coolant determined. If this target temperature is lower than the actual temperature of the coolant, the expansion element of the thermostatic valve 15 over the line 17 heated.

In Fig. 2 ist eine mögliche Kühlmitteltemperaturregelung dargestellt, bei der das tatsächliche Einschalten der Beheizung des Dehnstoffelementes ("Dehnstoffelement beheizen") über eine besonders vorteilhafte logische Verknüpfung mehrerer Einzelbedingungen bezogen auf verschiedene Betriebs- und Umweltgrößen des Kraftfahrzeuges gesteuert wird. Eine derartige Regellogik ist beispielsweise in der Steuereinheit 18 gespeichert, wobei die Steuereinheit 18 beispielsweise in einem ohnehin vorhandenen Steuergerät integriert oder auch ein eigenes integriertes Bauteil im Thermostatventil selbst sein kann.2 is a possible coolant temperature control shown where the heating is actually switched on of the expansion element ("heat expansion element") via a particularly advantageous logical link several individual conditions related to different Operating and environmental variables of the motor vehicle controlled becomes. Such control logic is for example in the Control unit 18 is stored, the control unit 18 for example in an already existing control unit integrated or a separate integrated component in the Thermostatic valve itself can be.

In Fig. 2 werden insbesondere die Betriebs- und Umweltgrößen Drosselklappenöffnungswinkels DK, Motordrehzahl n, Ist-Temperatur des Kühlmittels TKist, Fahrzeuggeschwindigkeit v und Ansauglufttemperatur TS, die beispielsweise in Form von Sensorsignalen vorliegen, zur Regelung der Kühlmitteltemperatur verarbeitet. Über die reinen Sensorsignale der Betriebs- und Umweltgrößen des Kraftfahrzeuges hinaus können auch Zustandssignale, die aus einer Verknüpfung der einzelnen Sensorsignale bzw. der Betrieb- und Umweltgrößen gebildet wurden, in der Regelung verarbeitet werden. Ein derartiges Zustandssignal ist in diesem Beispiel das Signal Leerlauf LL bei Fahrzeugstillstand, wobei dieses Signal beispielsweise aus der Fahrzeuggeschwindigkeit v und der Motordrehzahl n gebildet wird. Es sind jedoch auch noch weitere Zustandssignale möglich, die in einer Regelung der Kühlmitteltemperatur verwendet werden, wie beispielsweise der bereits erwähnte Lastzustand des Verbrennungsmotors sowie Bergfahrt oder Hängerbetrieb, die vorzugsweise aus den Betriebsgrößen Drosselklappenöffnungswinkel DK und Fahrzeuggeschwindigkeit v gebildet werden.In FIG. 2, the operating and environmental variables throttle valve opening angle DK, engine speed n, actual temperature of the coolant T Kist , vehicle speed v and intake air temperature T S , which are present, for example, in the form of sensor signals, are processed to control the coolant temperature. In addition to the pure sensor signals of the operating and environmental variables of the motor vehicle, status signals which were formed from a combination of the individual sensor signals or the operating and environmental variables can also be processed in the control system. In this example, such a status signal is the idle signal LL when the vehicle is at a standstill, this signal being formed, for example, from the vehicle speed v and the engine speed n. However, other status signals are also possible, which are used in a control of the coolant temperature, such as, for example, the load condition of the internal combustion engine already mentioned, as well as driving uphill or in a trailer, which are preferably formed from the operating variables throttle valve opening angle DK and vehicle speed v.

In Fig. 2 werden die Sensorsignale Drosselklappenöffnungswinkel DK und Motordrehzahl n herangezogen, um aus einem Kennfeld K die Soll-Temperatur TKsoll des Kühlmittels zu den durch den Drosselklappenöffnungswinkel DK und die Motordrehzahl n bestimmten Betriebspunkten zu ermitteln. Die so bestimmte Soll-Temperatur des Kühlmittels TKsoll wird mit der Ist-Temperatur des Kühlmittels TKist verglichen. Ist die Ist-Temperatur TKist größer als die Soll-Temperatur TKsoll wird die Beheizung des Dehnstoffelements freigegeben. Eine Freigabe entspricht hier einer Freigabeoption F (eingekreist), nicht zwingend einem tatsächlichen Beheizen.2, the sensor signals throttle valve opening angle DK and engine speed n are used to determine the setpoint temperature T Ksoll of the coolant from a characteristic map K at the operating points determined by the throttle valve opening angle DK and the engine speed n. The target temperature of the coolant T Ksoll determined in this way is compared with the actual temperature of the coolant T Kist . If the actual temperature T Kist is greater than the target temperature T Ksoll , the heating of the expansion element is released. A release corresponds to a release option F (circled), not necessarily an actual heating.

Weiterhin wird in einem Hystereseglied VT beobachtet, ob sich die Differenz δT zwischen der Ist- und Soll-Temperatur um mehr als eine vorgegebene Differenz δTH ändert. Nur dann wird die Freigabeoption F zum Beheizen des Dehnstoffelementes aufrechterhalten. Dazu wird am Ausgang des Hysteresegliedes VT ein logisches High-Signal abgegeben. Dieses Ausgangssignal des Hysteresegliedes VT wird an die Eingänge der Und-Gatter UND-1 und UND-3 herangeführt.Furthermore, it is observed in a hysteresis element VT whether the difference δT between the actual and target temperature changes by more than a predetermined difference δT H. Only then is the release option F for heating the expansion element maintained. For this purpose, a logic high signal is emitted at the output of the hysteresis element VT. This output signal of the hysteresis element VT is fed to the inputs of the AND gates AND-1 and AND-3.

Generell entspricht in diesem Ausführungsbeispiel ein logisches High-Signal einer Freigabeoption F.In this exemplary embodiment, a logic corresponds in general High signal of a release option F.

Weitere Freigabeoptionen F zum Einschalten der Beheizung des Dehnstoffelements werden in Abhängigkeit von der Ansauglufttemperatur TS erzeugt. Die Beheizung des Dehnstoffelements in Abhängigkeit von der Ansauglufttemperatur TS soll nur dann freigegeben werden, wenn zumindest eine der drei Schwellen TS1, TS2 und TS3 überschritten ist. Bei Überschreiten der ersten Schwelle TS1 wird ein logisches High-Signal an das UND-Gatter UND-1, bei Überschreiten der zweiten Schwelle TS2 wird ein logisches High-Signal an das UND-Gatter UND-2 und bei Überschreiten der dritten Schwelle TS3 ein logisches High-Signal an das UND-Gatter UND-3 abgegeben.Further release options F for switching on the heating of the expansion element are generated as a function of the intake air temperature T S. The heating of the expansion element depending on the intake air temperature T S should only be released if at least one of the three thresholds TS1, TS2 and TS3 is exceeded. When the first threshold TS1 is exceeded, a logic high signal is sent to the AND gate AND-1, when the second threshold TS2 is exceeded a logic high signal is sent to the AND gate UND-2 and when the third threshold TS3 is exceeded a logic signal High signal sent to the AND gate UND-3.

Weiterhin wird bei Leerlauf im Stillstand des Fahrzeuges das Zustandssignal LL (bei v = 0) in Form eines logischen High-Signals an das UND-Gatter UND-3 herangeführt.Furthermore, when the vehicle is idling, the vehicle is stationary the status signal LL (at v = 0) in the form of a logical High signals brought up to the AND gate AND-3.

Darüber hinaus kann nach diesem Ausführungsbeispiel die Freigabeoption F der Beheizung des Dehnstoffelements auch vom Überschreiten einer Fahrzeuggeschwindigkeitsschwelle VS der Fahrzeuggeschwindigkeit v abhängen, worauf ein logisches High-Signal vom Ausgang eines weiteren Hysteresegliedes VV an einen zweiten Eingang des UND-Gatters UND-2 ausgegeben wird. Zum Sperren (Sperroption) der Beheizung wird im Hystereseglied VV beobachtet, ob die Fahrzeuggeschwindigkeit v die Schwelle VS um einen Differenzwert δvH unterschritten hat. Erst dann wird wieder ein logisches Low-Signal (Sperroption) vom Ausgang des Hysteresegliedes VV an den zweiten Eingang des UND-Gatters UND-2 ausgegeben.In addition, according to this exemplary embodiment, the release option F for heating the expansion element can also depend on a vehicle speed threshold VS of the vehicle speed v being exceeded, whereupon a logic high signal is output from the output of a further hysteresis element VV to a second input of the AND gate UND-2. To block (block) the heating, it is observed in the hysteresis element VV whether the vehicle speed v has fallen below the threshold VS by a difference value δv H. Only then is a logic low signal (blocking option) again output from the output of the hysteresis element VV to the second input of the AND gate UND-2.

Die Hystereseglieder VT und VV können auch Zeitverzögerungsglieder sein oder mit Zeitverzögerungsgliedern verbunden werden.The hysteresis elements VT and VV can also be time delay elements be or connected with time delay elements will.

Die Ausgänge der UND-Gatter UND-1 bis UND-3 sind mit drei Eingängen eines ODER-Gatters ODER verbunden. Wenn auf der Ausgangsleitung zumindest eines UND-Gatters ein logisches High-Signal anliegt, wird auch am Ausgang des ODER-Gatters eine Freigabeoption F in Form eines logischen High-Signals erzeugt.The outputs of the AND gates UND-1 to AND-3 are three Inputs of an OR gate OR connected. If on the Output line of at least one AND gate a logic High signal is also present at the output of the OR gate a release option F in the form of a logical high signal generated.

Darüber hinaus kann noch ein Zeitverzögerungsglied δt am Ausgang des ODER-Gatters vorgesehen sein, durch das eine Freigabeoption F am Ausgang des ODER-Gatters nur dann zum tatsächlichen Beheizen des Dehnstoffelementes führt, wenn diese Freigabeoption F für eine vorgegebenen Zeit δt anliegt, um bei kurzfristigen Änderungen ein ständiges Ein- und Ausschalten der Beheizung zu verhindern.In addition, a time delay element δt on Output of the OR gate can be provided through the one Release option F at the output of the OR gate only then actual heating of the expansion element leads, if this release option F is present for a predetermined time δt, in order to keep a constant and to prevent the heating from being switched off.

Die Fahrzeuggeschwindigkeitsschwelle VS ist vorzugsweise eine Fahrzeuggeschwindigkeit v, bei der der Verbrennungsmotor thermisch stark belastet wird. Die Schwellen TS1 bis TS3 der Ansauglufttemperatur TS werden beispielsweise in Abhängigkeit von der Länderausführung des Fahrzeuges oder der Bauart des Verbrennungsmotors oder des Kühlers abgestimmt. Die Schwelle TS3 wird beispielsweise niedriger liegen als die Schwellen TS1 und TS2, da in Verbindung mit dem Leerlauf des Motors, bei dem keine zusätzliche Kühlung durch Fahrtwind auftritt, eine stärkere Kühlung erforderlich ist, als beispielsweise bei hohen Fahrzeuggeschwindigkeiten. Daher wird beispielsweise die Schwelle TS2, die in Verbindung mit der Fahrzeuggeschwindigkeitsschwelle VS ausgelegt wird, höher als die Schwellen TS1 und TS3 sein, da bei erhöhter Fahrzeuggeschwindigkeit zusätzlich Kühlung durch den Fahrtwind auftritt. Im allgemeinen werden die Fahrzeug- und Ansauglufttemperaturschwellen jedoch empirisch in Versuchen ermittelt werden. Wichtig ist beispielsweise bei sehr kalten Umgebungs- bzw. Ansauglufttemperaturen (z.B. in "Nordländern"), den Kühlerbetrieb in Abhängigkeit von der Ansaug- oder Umgebungstemperatur zu steuern, um einem Thermoschock des Verbrennungsmotors entgegenzuwirken. Bei. sehr heißen Umgebungs- bzw. Ansauglufttemperaturen (z.B. in "Tropenländern") kann mit der Regelung der Kühlmitteltemperatur in Abhängigkeit von der Ansaug- oder Umgebungstemperatur eine Anfahrschwäche bei Heißleerlaufbzw. Stop-and-go-Betrieb vermieden werden. The vehicle speed threshold VS is preferably a vehicle speed v at which the internal combustion engine is subjected to high thermal loads. The thresholds TS1 to TS3 of the intake air temperature T S are coordinated, for example, depending on the country version of the vehicle or the type of combustion engine or cooler. The threshold TS3 will, for example, be lower than the thresholds TS1 and TS2, since in connection with the idling of the engine, in which no additional cooling occurs due to the wind, more cooling is required than, for example, at high vehicle speeds. Therefore, for example, the threshold TS2, which is designed in conjunction with the vehicle speed threshold VS, will be higher than the thresholds TS1 and TS3, since additional cooling occurs due to the wind at higher vehicle speeds. In general, however, vehicle and intake air temperature thresholds will be empirically determined in trials. It is important, for example, in very cold ambient or intake air temperatures (for example in "northern countries") to control the cooler operation as a function of the intake or ambient temperature in order to counter thermal shock of the internal combustion engine. At. very hot ambient or intake air temperatures (eg in "tropical countries") can regulate the coolant temperature depending on the intake or ambient temperature, a weakness in hot idling or Stop-and-go operations can be avoided.

Ergänzend wird darauf hingewiesen, daß in weiteren Ausführungsformen der Erfindung auch bei einer zu einer Freigabeoption F führenden Erfüllung nur einer der in Fig. 2 dargestellten Bedingungen die Beheizung tatsächlich eingeschaltet werden kann. D.h., daß beispielsweise die in Fig. 2 mit eingekreistem F gekennzeichneten Punkte jeder für sich auch direkt mit der Einschaltvorrichtung der Beheizung des Dehnstoffelementes verbunden sein können.In addition, it is pointed out that in other embodiments the invention also at one to one Release option F leading fulfillment of only one of the in Fig. 2 conditions actually heating can be switched on. That is, for example the points marked with circled F in FIG. 2 each one directly with the switch-on device the heating of the expansion element can be connected.

In Fig. 3 ist in einem Diagramm der Verlauf der Kühlmitteltemperatur TK über der Zeit t bei Teillast und Vollast dargestellt, wie er sich mittels der erfindungsgemäßen Kühlanlage erreichen läßt. Das Dehnstoffelement des Thermostatventils 15 wird beispielsweise durch die Zusammmensetzung des Dehnstoffes auf eine obere Arbeitsgrenztemperatur TAG ausgelegt, die hier einer Kühlmitteltemperatur von ca. 105°C im eingeregelten Mischbetrieb ist. Diese Temperatur ist mit einer oberen Linie dargestellt. Ein Temperaturniveau von 105°C im Teillastbereich ist zweckmäßig, um durch Verminderung von Reibung oder dgl. den Kraftstoffverbrauch zu reduzieren und gleichzeitig die Abgaszusammensetzung zu verbessern. Grundsätzlich soll die Kühlmitteltemperatur zur Verbrauchsoptimierung immer so heiß wie möglich, aber bei Leistungsanforderungen im Vollastbereich zur Verbesserung der Füllung kühl sein.
Bei einem Kaltstart des Verbrennungsmotors wird im Bereich A bis B zunächst im Warmlaufbetrieb und anschließend im Mischbetrieb während eines Teillastbetriebes die Kühlmitteltemperatur TK mit einem höheren Temperaturgradienten dT/dt auf das Temperaturniveau von 105°C gebracht, als bei übrigen Kühlanlagen möglich ist. Dabei wird das Dehnstoffelement des Thermostatventils 15 ausschließlich durch die Kühlmitteltemperatur TK erwärmt. 3 shows a diagram of the course of the coolant temperature T K over time t at part load and full load, as can be achieved by means of the cooling system according to the invention. The expansion element of the thermostatic valve 15 is designed, for example, by the composition of the expansion material to an upper working limit temperature T AG , which here is a coolant temperature of approximately 105 ° C. in the regulated mixed operation. This temperature is shown with an upper line. A temperature level of 105 ° C in the partial load range is expedient in order to reduce fuel consumption by reducing friction or the like and at the same time to improve the exhaust gas composition. Basically, the coolant temperature should always be as hot as possible to optimize consumption, but should be cool to improve the filling in the case of performance requirements in the full-load range.
When the internal combustion engine is cold started, the coolant temperature T K is brought to the temperature level of 105 ° C with a higher temperature gradient dT / dt than is possible with other cooling systems in warm-up mode and then in mixed mode during part-load operation. The expansion element of the thermostatic valve 15 is heated exclusively by the coolant temperature T K.

Das Dehnstoffelement ist so ausgelegt, daß bei hier 105 °C der mögliche Verstellweg des Ventils bzw. der maximal mögliche Öffnungsquerschnitt noch nicht eingestellt ist. So kann bei Vollast im Bereich zwischen C und E das Dehnstoffelement z.B. so stark beheizt werden, daß zur möglichst schnellen Abkühlung ein maximaler Öffnungsquerschnitt zum Kühler hin eingestellt wird und dadurch vollständig in den Kühlerbetrieb übergegangen wird. In diesem Beispiel wird nach einer kurzen Abkühlzeit ein Temperaturniveau von ca. 70°C erreicht. Geht der Betrieb des Verbrennungsmotors 10 von Vollast bei Punkt E wieder auf Teillast zurück, so wird die Zufuhr von elektrischer Energie zum Dehnstoffelement unterbrochen. Das nun kältere Kühlmittel, das das Dehnstoffelement umströmt, kühlt den Dehnstoff ab und bewirkt, daß sich wieder eine Verstellung des Thermostatventils durch das Dehnstoffelement allein in Abhängigkeit von der Kühlmitteltemperatur TK einstellt. Das Thermostatventil regelt dann wieder die Kühlmitteltemperatur TK und damit die Temperatur des Verbrennungsmotors 10 auf das Temperaturniveau von 105°C ein.The expansion element is designed so that at 105 ° C here the possible adjustment path of the valve or the maximum possible opening cross section has not yet been set. For example, at full load in the area between C and E, the expansion element can be heated so strongly, for example, that a maximum opening cross-section to the cooler is set in order to cool down as quickly as possible, thereby completely switching to cooler operation. In this example, a temperature level of approx. 70 ° C is reached after a short cooling time. If the operation of the internal combustion engine 10 goes from full load at point E back to partial load, the supply of electrical energy to the expansion element is interrupted. The now cooler coolant, which flows around the expansion element, cools the expansion material and causes the thermostatic valve to be adjusted again by the expansion element solely as a function of the coolant temperature T K. The thermostatic valve then regulates the coolant temperature T K and thus the temperature of the internal combustion engine 10 to the temperature level of 105 ° C.

Die Absenkung der Kühlmitteltemperatur TK im Vollastbetrieb auf beispielsweise ein Temperaturniveau von ca. 70°C hat den Vorteil, daß dann vom Verbrennungsmotor 10 die volle Leistung erbracht werden kann. Es wird damit vermieden, daß aufgrund einer zu hohen Temperatur ein geringerer Füllungsgrad bei der Verbrennung erhalten wird, der zu einer Leistungsverminderung führt. Die geregelte Absenkung der Kühlmitteltemperatur TK durch Beheizung des Dehnstoffelements kann jedoch auch abhängig von verschiedenen anderen Betriebs- und/oder Umweltgrößen des Kraftfahrzeuges geregelt werden.Lowering the coolant temperature T K in full-load operation to, for example, a temperature level of approximately 70 ° C. has the advantage that the internal combustion engine 10 can then provide the full power. It is thus avoided that, due to an excessively high temperature, a lower degree of filling during combustion is obtained, which leads to a reduction in performance. However, the regulated lowering of the coolant temperature T K by heating the expansion element can also be regulated depending on various other operating and / or environmental variables of the motor vehicle.

Vollast kann beispielsweise durch Größen wie die Fahrzeuggeschwindigkeit, die Motordrehzahl oder den Drosselklappenwinkel erkannt werden. Beispielsweise ist es auch sinnvoll, bei sehr niedrigen Fahrzeuggeschwindigkeiten oder im Leerlauf und bei Stillstand des Fahrzeugs sowie bei hohen Außentemperaturen, bei Bergfahrten oder im Hängerbetrieb die Kühlmitteltemperatur TK durch Beheizen des Dehnstoffelementes abzusenken.Full load can be recognized, for example, by variables such as the vehicle speed, the engine speed or the throttle valve angle. For example, it is also sensible to lower the coolant temperature T K by heating the expansion element at very low vehicle speeds or when the vehicle is idling and at a standstill as well as at high outside temperatures, when driving uphill or in trailer operation.

In Fig. 4 ist ein Kennfeld zur Bestimmung einzelner Soll-Temperaturen TKsoll des Kühlmittels bei einzelnen Betriebspunkten in Abhängigkeit von der Fahrzeuggeschwindigkeit V und dem Lastzustand LAST dargestellt. Dabei kann der Lastzustand LAST beispielsweise wiederum in Abhängigkeit des Drosselklappenöffnungswinkels und der Drehzahl oder der Luftmasse im Ansaugrohr bestimmt sein.4 shows a map for determining individual target temperatures T Ksoll of the coolant at individual operating points as a function of the vehicle speed V and the load state LAST. The load state LAST can in turn be determined, for example, as a function of the throttle valve opening angle and the speed or the air mass in the intake pipe.

Die jeweils einem durch je zwei Betriebsgrößen bestimmten Betriebspunkt zugeordnete Soll-Temperatur des Kühlmittels kann berechnet oder durch Versuche empirisch ermittelt werden. Es ist auch möglich, eine Soll-Temperatur des Kühlmittels in Abhängigkeit von mehreren Kennfeldern zu bestimmen, die verschiedene Betriebs- und/oder Umweltgrößen des Fahrzeuges verarbeiten.The one determined by two company sizes Setpoint temperature of the coolant assigned to the operating point can be calculated or empirically determined by experiment will. It is also possible to set a target temperature of the Coolant depending on several maps determine the different farm and / or environmental sizes process the vehicle.

Insbesondere ist es erfindungsgemäß auch möglich, über die Abstimmung eines Kennfeldes und durch Abstimmung der Schwellwerte eine Kühlanlage für verschiedene Ländervarianten zu erhalten, ohne die Hardware oder die Software der Kühlanlage zu ändern.In particular, it is also possible according to the invention to the coordination of a map and by coordination of the Threshold values of a cooling system for different country variants to get without the hardware or software to change the cooling system.

Claims (6)

  1. A cooling system for an internal combustion engine of a motor vehicle with a radiator and a thermostatic valve, with which the temperature of the cooling medium can be regulated in a hot operation, a mixed operation and a radiator operation, whereby the thermostatic valve includes an expansion element, which can be heated electrically to reduce the cooling medium temperature, whereby the cooling medium temperature (TK, TKist) is regulated in mixed operation by the design of the expansion element, without heating the expansion element. to a final temperature, and whereby a control unit (18) is provided, which depending on captured operational and/or environmental values (DK, n, v, Ts, LAST, TKist, LL) of the internal combustion engine (10) enables the heating of the expansion element, so as to transfer the mode of operation of the cooling system towards radiator operation, characterised in that the regulated final temperature without heating the expansion element corresponds to the upper limit of working temperature (TAG) and is provided in partial load operation and that in full load operation a target temperature (TKsoll) is prescribed for the enabling of the heating of the expansion element, which is lower than the upper limit of working temperature (TAG).
  2. A cooling system for an intemal combustion engine of a motor vehicle with a radiator and a thermostatic valve, with which the temperature of the cooling medium can be regulated in a hot operation, a mixed operation and a radiator operation, whereby the thermostatic valve includes an expansion element, which can be heated electrically to reduce the cooling medium temperature, whereby the cooling medium temperature (TK, TKist) is regulated in mixed operation by the design of the expansion element, without heating the expansion element, to a final temperature, and whereby a control unit (18) is provided, which depending on captured operational and/or environmental values (DK, n, v, Ts, LAST, TKist, LL) of the internal combustion engine (10) enables the heating of the expansion element, so as to transfer the mode of operation of the cooling system towards radiator operation, characterised in that the regulated final temperature without heating the expansion element corresponds to the upper limit of working temperature (TAG) and
    that the control unit (18) captures the actual temperature of the cooling medium (TK, TKist) as an operating value, compares this actual temperature with a target temperature (TKsoll) determined at least by the throttle flap opening angle (DK) and the speed of revolution of the motor (n) and if the actual temperature (TKist) lies above the target temperature (TKsoll) enables the heating of the expansion element
       and/or
    that the control unit (18) captures the vehicle speed (v) as an operating value and compares it with a vehicle speed threshold (VS) and enables the heating of the expansion element if the vehicle speed threshold is exceeded
       and/or
    that the control unit (18) captures the actual temperature (TS) of the inducted air or the ambient air, compares this actual temperature (TS) with a predetermined threshold value (TS1; TS2; TS3) and enables the heating of the expansion element if this threshold value is exceeded.
  3. A cooling system according to Claim or 2, characterised in that the control unit (18) captures the speed of revolution (n) of the intemal combustion engine, the throttle flap opening angle (DK), the vehicle speed (v) and/or the loading condition (LAST) of the internal combustion engine (10) as operating values and depending on at least two of these operating values determines the target temperature (TKsoll) of the cooling medium in the form of a set of curves.
  4. A cooling system according to one of Claims 1 to 3, characterised in that the control unit (18) enables the heating of the expansion element on fulfilment of one of the conditions for enabling the heating corresponding to an operating value or environmental value hysteresis (δVH, δTH) and/or with a delay in accordance with a predetermined time window (δt).
  5. A cooling system according to one of Claims 1 to 4, characterised in that the control unit (18) shuts off the heating of the expansion element on fulfilment of one of the conditions for cutting off the heating corresponding to an operating value or environmental value hysteresis (δVH, δTH) and/or with a delay in accordance with a predetermined time window (δt).
  6. A cooling system according to one of Claims 1 to 5, characterised in that the control unit (18) continously determines a current maximum temperature of the cooling medium depending on the operating and/or environmental values (DK, n, v, Ts, LAST, TKist, LL), through which the target temperature (TKsoll) of the cooling medium is essentially determined at each time.
EP94108811A 1993-07-19 1994-06-08 Cooling system for an internal combustion engine Expired - Lifetime EP0640753B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4324178A DE4324178A1 (en) 1993-07-19 1993-07-19 Cooling system for an internal combustion engine of a motor vehicle with a thermostatic valve that contains an electrically heated expansion element
DE4324178 1993-07-19

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EP0640753A1 EP0640753A1 (en) 1995-03-01
EP0640753B1 true EP0640753B1 (en) 1998-08-12

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EP (1) EP0640753B1 (en)
JP (1) JP2662187B2 (en)
DE (2) DE4324178A1 (en)

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US5529025A (en) 1996-06-25
JP2662187B2 (en) 1997-10-08
EP0640753A1 (en) 1995-03-01
JPH0771251A (en) 1995-03-14
DE4324178A1 (en) 1995-01-26
DE59406657D1 (en) 1998-09-17

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