Extended fan run-on

Abstract

The invention relates to a fan run-on control which takes into account the energy input into the combustion engine in order to calculate the required run-on time of the fan. If the characteristics of the fan are known it is possible to calculate the required fan run-on time from the integral of the energy input into the combustion engine before the combustion engine was switched off, and the current operating data and ambient data of the combustion engine. Furthermore, by comparing the energy input into the combustion engine with the cooling performance of the cooling system over a specific period of time before the engine was switched off, it is possible to predict whether or not running-on of the fan will be necessary. There is always a risk of further subsequent heating whenever the energy input into the engine has been significantly greater than the cooling performance of the system before the engine was switched off. If the opposite is true, there may sometimes be no need for the fan to run on, or the fan run-on time can be much shorter than in previously known systems.

1 . Method for controlling a fan motor ( 4 ), in particular for a motor vehicle, in which at least one logic element (logic) is used to evaluate operating data and ambient data of a combustion engine ( 1 ) measured by an engine management system and to calculate a fan run-on time for the fan motor, characterized in that the fan run-on time is determined from the energy input into the combustion engine.  
     
     
         2 . The method as claimed in  claim 1 , characterized in that the energy input into the combustion engine ( 1 ) is determined from the mass air flow (MAF) and the speed of the combustion engine, the fuel injection quantity, the induced torque or the induced power of the combustion engine.  
     
     
         3 . The method as claimed in  claim 1 , characterized in that the energy input into the combustion engine is determined from an engine-specific air mass/engine speed-dependent temperature characteristics map ( 19 ).  
     
     
         4 . The method as claimed in  claim 3 , characterized in that the duration of the fan run-on time is calculated by integration of the energy inputs.  
     
     
         5 . The method as claimed in  claim 4 , characterized in that the integration is each time performed over a predetermined time interval and the integration result ( 27 ) is stored by intervals, the number of retroactively recorded interval-specific integration results being limited and the recorded interval-specific integration results each time being cyclically overwritten by the currently calculated integration results.  
     
     
         6 . The method as claimed in  claim 5 , characterized in that an average is formed from the interval-specific integration results ( 27 ).  
     
     
         7 . The method as claimed in  claim 1 , characterized in that in addition to the energy input into the combustion engine ( 2 ), characteristics maps for the air temperature and characteristics maps for the coolant temperature for determining the currently attainable cooling performance are also introduced into the calculation for determining the duration of the fan run-on time.  
     
     
         8 . The method as claimed in  claim 3 , characterized in that the air mass/engine speed-dependent temperature characteristics map ( 19 ) contains a family of characteristics for multiple temperature-critical components.  
     
     
         9 . The method as claimed in  claim 8 , characterized in that the family of characteristics is corrected by correction parameters for the outside air temperature, vehicle speed, fan activation, water temperature, intake air temperature, exhaust gas temperature or radiator shutter position.  
     
     
         10 . A device for calculating the run-on time of a fan motor ( 4 ), in particular for a motor vehicle, having at least one electronic storage medium and at last one electronic logic element (logic); 
 characteristics maps ( 19 ) of the operating state and operating conditions of a combustion engine being filed in the storage medium/media,    and calculations to determine the fan run-on time being performed in the electronic logic element (logic) by means of software programs or by means of logic elements, characterized in that the logic element is in communication with signal generators ( 17 ) for the volumetric efficiency of the combustion cylinders and for the speed of the combustion engine or the fuel injection quantity or the induced torque or the induced power of the combustion engine, and the fan run-on time is determined from the energy input into the combustion engine ( 2 ).    
     
     
         11 . The device as claimed in  claim 10 , characterized in that at least one characteristics map ( 19 ) is an air mass/engine speed-dependent temperature characteristics map.  
     
     
         12 . The device as claimed in  claim 10 , characterized in that the logic element comprises an integration stage ( 23 ) for the time integration of the energy inputs from the air mass/engine speed-dependent temperature characteristics map ( 19 ).  
       the energy inputs from the air mass/engine speed-dependent temperature characteristics map ( 19 ).  
     
     
         13 . The device as claimed in  claim 10 , characterized in that the logic element comprises a software programmed or hard-wired cyclical loop ( 29 ) for the storage of interval-specific integration results ( 27 ).  
     
     
         14 . The device as claimed in  claim 10 , characterized in that the logic element comprises software programmed or hard-wired averaging ( 33 ) for all registered interval-specific integration results.  
     
     
         15 . The device as claimed in  claim 10 , characterized in that the logic element is in communication with the engine management system ( 17 ) as signal generator.  
     
     
         16 . The device as claimed in  claim 1 , characterized in that the logic element (logic) is integrated into an engine management system ( 17 ).  
     
     
         17 . The device as claimed in  claim 10 , characterized in that the logic element (logic) contains characteristics maps of the air temperature and characteristics maps of the coolant temperature for determining the currently attainable cooling performance.  
     
     
         18 . The device as claimed in  claim 11 , characterized in that the air mass/engine speed-dependent temperature characteristics map comprises a family of curves of multiple temperature-critical components in the vehicle.  
     
     
         19 . The device as claimed in  claim 18 , characterized in that the family of characteristics is corrected by correction parameters for the outside air temperature, vehicle speed, fan activation, water temperature, intake air temperature, exhaust gas temperature or radiator shutter position.