Abstract: A system and method for selecting the operating mode of a variable displacement engine includes a controller with a stored engine map, an engine speed sensor, and an inferred desired fractional manifold vacuum which would be required for the engine to operate on a fractional number of cylinders, given the driver's current torque requirements, a specific emissions calibration, and environmental conditions, deriving this inferred desired fractional manifold vacuum from stored information and assorted engine sensor input. The system compares its inferred desired fractional manifold vacuum and current engine speed to one or more stored maps of inferred desired fractional manifold vacuum versus engine speed in order to decide which operating mode should be selected.

Abstract: An Electronic Engine Controller (EEC) controls the operation of an electronically controlled throttle. The EEC generates a predicted desired throttle angle value as a function of upstream and downstream air pressure values, an air temperature value and a desired airflow value. A predicted actual throttle angle value is generated as a function of the upstream and downstream air pressure values, an air temperature value and an actual airflow value. A throttle angle difference value is generated as a function of the difference between the predicted desired throttle angle value and the predicted actual throttle angle value. A PID controller is employed to generate a throttle angle change value. The throttle angle change value is then added to the predicted desired throttle angle change value to generate a throttle angle control value, indicative of a position for said throttle. The throttle angle is then altered to a position corresponding to the throttle angle control value.

Abstract: A system for selecting the operating mode of a variable displacement engine includes a vacuum analyzer, a flow analyzer, and a controller for determining whether the variable displacement engine should be operated on a fractional number of cylinders. The vacuum analyzer generates a vacuum recommendation signal indicating whether a fractionally operating variable displacement engine can accommodate the inferred desired fractional manifold vacuum with respect to a desired torque and a specific emissions calibration. The flow analyzer generates a flow recommendation signal indicating whether a fractionally operating variable displacement engine can accommodate a desired mass air flow and a desired exhaust gas recirculation flow with respect to a desired torque, a specific emissions calibration, and environmental conditions. The controller evaluates the vacuum and flow recommendation signals no determine the operating mode of the engine.

Abstract: An apparatus for determining a number of cylinders to operate in a variable displacement engine includes a signal representative of air charge temperature, a signal representative of barometric pressure, a desired mass air flow evaluator, a maximum mass air flow evaluator, a desired exhaust gas recirculation flow evaluator, a maximum exhaust gas recirculation flow evaluator, and a controller. The controller compares the desired mass air flow to the maximum mass air flow, generating a mass air flow error signal if desired mass air flow error exceeds maximum mass air flow error. The controller also compares the desired exhaust gas recirculation flow to the maximum exhaust gas recirculation flow, generating an exhaust gas recirculation flow error signal if desired exhaust gas recirculation flow exceeds maximum exhaust gas recirculation flow.