Variable geometry turbocharger control system

Abstract

The disclosure relates to a control system for a turbo-charged engine having a variable geometry turbine driving a compressor. An intake manifold temperature sensor senses an intake manifold temperature. An intake manifold pressure sensor senses an intake manifold pressure. A turbine inlet temperature sensor senses a turbine inlet temperature. A turbine inlet pressure sensor senses a turbine inlet pressure. A control unit generates a vane position control signal which is applied to a vane control input of the turbine. The control unit generates the vane position control signal as a function of turbine inlet temperature and turbine inlet pressure.

We claim: 
     
         1 . In a turbo-charged engine having a variable geometry turbine driving a compressor, an intake manifold receiving intake air from the compressor, and an exhaust manifold for supplying exhaust to an input of the variable geometry turbine, a control system comprising:
 an intake manifold temperature sensor for sensing an intake manifold temperature T(man);   an intake manifold pressure sensor for sensing an intake manifold pressure P(man);   a turbine inlet temperature sensor for sensing a turbine inlet temperature T(in);   a turbine inlet pressure sensor for sensing a turbine inlet pressure P(in); and   a control unit for generating a vane position control signal which is applied to a vane control input of the variable geometry turbine, the control unit generating the vane position control signal as a function of turbine inlet temperature and turbine inlet pressure.   
     
     
         2 . The control system of  claim 1 , wherein:
 the control unit determines an estimated mass flow rate m in  of exhaust through the turbine as a function sensed turbine inlet temperature, turbine inlet pressure and a fuel rate; and   the control unit generating a corrected mass flow rate value by the equation m in ×(T(in)) 1/2 /P(in); and   the control unit determines the vane position control signal as a function of the corrected mass flow rate value.   
     
     
         3 . The control system of  claim 2 , further comprising:
 a turbine vane position sensor, the control unit controlling turbine vane position as a function of the vane position control signal and sensed vane position.   
     
     
         4 . The control system of  claim 1 , wherein:
 the control unit determines an estimated mass flow rate m in  of exhaust through the turbine as a function sensed turbine inlet temperature, turbine inlet pressure and a fuel rate; and   the control unit generating a corrected mass flow rate value by the equation m in ×(T(in)) 1/2 /P(in); and   the control unit determines the vane position control signal from a look-up table which associates a plurality of corrected mass flow rate values with a plurality of optimal vane position values.   
     
     
         5 . The control system of  claim 4 , further comprising:
 a turbine vane position sensor, the control unit controlling turbine vane position as a function of the vane position control signal and sensed vane position.   
     
     
         6 . The control system of  claim 1 , further comprising:
 a charge air cooler between the compressor and the intake manifold.   
     
     
         7 . The control system of  claim 1 , wherein:
 the control unit prevents generation of the corrected mass flow rate value if a requested fueling is not greater than a maximum fueling.   
     
     
         8 . In a turbo-charged engine having a variable geometry turbine driving a compressor, an intake manifold receiving intake air from the compressor, and an exhaust manifold for supplying exhaust to an input of the variable geometry turbine, a control system comprising:
 a turbine inlet temperature sensor for sensing a turbine inlet temperature T(in);   a turbine inlet pressure sensor for sensing a turbine inlet pressure P(in); and   a control unit for generating a vane position control signal which is applied to a vane control input of the variable geometry turbine, the control unit generating the vane position control signal as a function of mass flow rate of exhaust through the turbine, turbine inlet temperature and turbine inlet pressure.   
     
     
         9 . The control system of  claim 8 , wherein:
 the control unit determines a corrected mass flow rate value from the equation corrected mass flow rate=estimated mass flow rate×(T(in)) 1/2 /P(in); and   the control unit determines the vane position control signal from a look-up table which associates a plurality of corrected mass flow rate values with a plurality of optimal vane position values.   
     
     
         10 . The control system of  claim 8 , wherein:
 the control unit prevents generation of the corrected mass flow rate value if a requested fueling is not greater than a maximum fueling.