Fan system and method for controlling a fan motor

Abstract

In a fan system for an internal combustion engine of a motor vehicle, having an electrical fan motor with a commutator, and having a control unit which detects a fault in the fan motor and switches said motor to a voltage-free state if the motor current reaches a predetermined load-dependent switch-off value, the invention proposes that the control unit controls the fan motor with at least a virtually maximum power for a predetermined period of time if the motor current reaches a load-dependent switching value which is lower than the associated switch-off value by a predetermined amount. As a result, the fan motor is not switched off in an undesirable manner if only contamination, but not blocking, is present.

1 . A fan system for carrying out controlled cooling for an internal combustion engine of a motor vehicle, having an electrical fan motor which has a commutator, and having a control unit for controlling the fan motor, the control unit being configured in such a manner that it detects a fault in the fan motor and switches said motor to a voltage-free state if the motor current reaches a predetermined load-dependent switch-off value, characterized in that the control unit controls the fan motor with at least a virtually maximum power for a predetermined period of time if the motor current reaches a load-dependent switching value which is lower than the associated switch-off value by a predetermined amount. 
     
     
         2 . The fan system according to  claim 1 , characterized in that the switching values are each 5 to 20% lower than the associated switch-off values. 
     
     
         3 . The fan system according to  claim 2 , characterized in that the switching values are each approximately 10% lower than the associated switch-off values. 
     
     
         4 . The fan system according to  claim 1 , characterized in that the predetermined period of time is less than 60 seconds, preferably approximately 10 seconds. 
     
     
         5 . The fan system according to  claim 1 , characterized in that the switch-off values and/or the switching values are each stored in the form of a characteristic curve in the control unit. 
     
     
         6 . A method for controlling a DC fan motor for an internal combustion engine of a motor vehicle, an item of information relating to the current through the fan motor being determined, and a fault in the fan motor being detected and the fan motor being switched off if the motor current reaches a predetermined load-dependent switch-off value, characterized in that the fan motor is controlled with at least a virtually maximum power for a predetermined period of time if the motor current reaches a load-dependent switching value which is lower than the associated switch-off value by a predetermined amount. 
     
     
         7 . The method according to  claim 6 , characterized in that the switching values are each selected to be 5 to 20%, in particular approximately 10%, lower than the associated switch-off values.