Hybrid modeling and control of disc engines

In a DISC engine system controlled by a powertrain control module which receives as inputs a plurality of engine operating parameters and outputs a plurality of calibration setpoints, said powertrain control module including a microprocessor and associated memory, a method of controlling said DISC engine comprising the steps of:

• inputting into a mathematical model of said DISC engine said plurality of engine operating parameters, said mathematical model including an indicated engine torque value according to the following equation:
• Ti=(at+bt(δ−δMBT)2)Wf
• wherein Wf is the fueling rate, δ−δMBT is the spark timing deviation from a desired setting, and at, bt are coefficients defined by the following equations:
• a t ⁡ ( N , r c ) = f 0 a t + f 1 a t ⁢ N + f 2 a t N + f 3 a t ⁢ r c b t ⁡ ( N , r c ⁢ F r ) = f 0 b t + f 1 b t ⁢ r c + f 2 b t ⁢ F r + f 3 b t ⁢ N + f 4 b t N + f 5 b t ⁢ F r ⁢ N
• wherein N is the engine speed, rc is the ratio of air charge to fuel and Fr is the ratio of burned gas to air charge defined by the following equations:
• r c = ( 1 + r - r s 1 + r ⁢ E 100 ) ⁢ r , ⁢ F r = 1 + r s 1 + r ⁢ ( E / 100 )
• wherein r is the measured exhaust air/fuel ratio and E is the EGR percentage wherein at and bt depend upon the combustion mode of said engine;
• calculating calibration setpoints for air/fuel ratio exhaust gas recirculation rate and the spark set point for said DISC engine with said mathematical model as a function of said plurality of engine operating parameters;
• and
• outputting said calibration setpoints to the respective associated engine control subsystems.

A control system for a vehicle having a direct injection stratified charge (DISC) engine coupled to a lean NOx trap that is periodically purged, the system comprising:

• an engine torque model representing the torque characteristics of said DISC engine, said engine torque model receiving as an input a first plurality of engine operating parameters and generating as an output an expected engine torque value;
• a feedgas emissions model representing the emissions output of said DISC engine, said feedgas generation model receiving as an input a second plurality of engine operating parameters and generating as an output an HC value, CO value and NOx value;
• and
• an exhaust gas temperature model representing the exhaust gas temperature of said DISC engine, said exhaust gas temperature model receiving as an input a third plurality of engine operating parameters and generating as an output an exhaust gas temperature value.