Bradford A Lessard

US Patent:

53906519, Feb 21, 1995

Filed:

Oct 29, 1993

Appl. No.:

8/145391

Inventors:

Stephen H. Nussbaum - Temecula CA
Bradford A. Lessard - Santee CA

Assignee:

Precision Engine Controls Corporation - San Diego CA

International Classification:

F02M 700

US Classification:

123694

Abstract:

Apparatus, and a corresponding method for its operation, for controlling the air/fuel ratio in a large engine having one or more banks of cylinders with separate intake and exhaust manifolds. Oxygen sensors in the manifolds are sampled periodically to provide the apparatus with an indication of the level of oxygen, and therefore an indication of the level of various pollutants, in exhaust gases discharged from the engine. The apparatus, preferably in microprocessor form, computes a fuel control correction based on the difference between the sensed oxygen level and a desired oxygen level in each exhaust manifold. The correction is applied in the form of a change to the pulse width of a binary control signal applied to a solenoid valve. In the illustrative embodiment, the solenoid valve is coupled to a fuel pressure regulator and functions to vent an air chamber in the regulator when the solenoid is actuated. Changing the pulse width of the control signal varies the average fuel pressure and thereby controls the air/fuel ratio, which in turn corrects the oxygen level in the exhaust manifold.