The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 17, 1987
Filed:
Feb. 28, 1986
Toyoaki Nakagawa, Yokohama City, JP;
Shisei Kai, Yokosuka City, JP;
Nissan Motor Co., Ltd., Yokohama City, JP;
Abstract
The invention relates to a control system for feedback control of the air/fuel ratio in an internal combustion engine by using a solid electrolyte oxygen sensor to sense oxygen in the exhaust gas. The oxygen sensor is of the type having an oxygen concentration cell and an oxygen ion pump cell to which a pumping current is supplied to vary the partial pressure of oxygen in the exhaust gas admitted in a measurement space in the sensor. The pumping current is controlled so as to nullify a difference between the output voltage of the oxygen concentration cell and a target voltage. A signal derived from the controlled pumping current is used as an air/fuel ratio signal on the premise that a definite correlation exists between the magnitude of the pumping current and the oxygen concentration in the exhaust gas. To commence feedback control of the air/fuel ratio soon after starting the engine and after establishment of the definite correlation without unnecessary delay, the control system includes discrimination means for forming a judgment that the expected definite correlation has been established if the output voltage of the oxygen concentration cell surely falls within a predetermined tolerance range containing the target voltage. When such a judgment is formed the feedback control is immediately commenced.