Closed loop air/fuel ratio controller with asymmetrical proportional term
Patent
·
OSTI ID:6832737
A closed loop air/fuel ratio controller for an internal combustion engine includes a control circuit responsive to the output of an exhaust gas sensor representing at least the sense of deviation of the air/fuel ratio of the mixture supplied to the engine from stoichiometry and provides a control signal which is used to adjust the air/fuel ratio of the mixture supplied to the engine in direction tending to restore a stoichiometric air/fuel ratio. The control signal includes an integral correction term and an asymmetrical proportional correction term that abruptly shifts the value of the control signal upon a detected change in at least one direction in the sense of the deviation of the air/fuel ratio from a stoichiometric air/fuel ratio. The asymmetrical proportional term provides either singularly or in combination with an asymmetrical integral term a scheduled air/fuel ratio offset from the stoichiometric air/fuel ratio with the offset value being a function of the system gains and the limit cycle frequency of the control signal that is determined primarily by the transport delay through the engine and exhaust system.
- Assignee:
- General Motors Corp
- Patent Number(s):
- US 4228775
- OSTI ID:
- 6832737
- Country of Publication:
- United States
- Language:
- English
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