EP0136144A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Engine air/fuel ratio sensing device
Assignee: Mitsubishi Electric Corp
•
Filing: 1984-09-17
•
Granted: —
•
Expires: 2004-09-17
Abstract
Abstract An engine air/fuel ratio sensing device measures the oxygen partial pressure or concentration in the exhaust gas of an engine, using a sensor which consists of an electrolyte oxygen pump cell 3 and an electrolyte oxygen sensor cell 4, the cells having a gap d therebetween. The oxygen pump cell pumps oxygen into ambient gas when electrically energized. The sensor cell produces an electromotive force when there is an oxygen partial pressure difference thereacross due to the pumping of the pump cell. The sensor is connected to a control circuit with differential amplifier A which receives as an input the sensor electromotive force for comparison with a predetermined reference voltage V. The amplifier continuously provides an output, used for driving a pumping current through the pump cell, until the electromotive force reaches the reference voltage at which an equilibrium condition for the pumping current is established. The differential amplifier accomplishes this function with a feedback series combination of a feedback resistor R2 and a feedback capacitor C.
Inventors
- 👤 Setsuhiro Shimomura
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 21:06
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/26; G01N27/416; G01N27/417
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
182 words
An engine air/fuel ratio sensing device comprising an air/fuel sensor having a gap (d) for introducing an exhaust gas of said engine, a solid electrolyte oxygen pump cell (3) for controlling the oxygen partial pressure within said gap, and a solid electrolyte oxygen sensor cell (4) for producing an electromotive force corresponding to the difference between the oxygen partial pressure in the exhaust gas within said gap and the oxygen partial pressure in the exhaust gas outside said gap; and a control circuit coupled to said sensor, including an input portion (A) for comparing a predetermined reference voltage (V) with the said electromotive force to continuously provide an output until the said electromotive force reaches the reference voltage, and an output portion (Tr) for driving a pump current through said oxygen pump cell (3) in response to the output of said input portion whereby the air/fuel ratio of the engine is detected according to an output corresponding to the pump current, characterised in that the input portion (A) has a transfer function of an amplifier component (R2) plus an integrator component (C).
Claim 2
Dependent Claim
182 words
An engine air/fuel ratio sensing device comprising an air/fuel sensor having a gap (d) for introducing an exhaust gas of said engine, a solid electrolyte oxygen pump cell (3) for controlling the oxygen partial pressure within said gap, and a solid electrolyte oxygen sensor cell (4) for producing an electromotive force corresponding to the difference between the oxygen partial pressure in the exhaust gas within said gap and the oxygen partial pressure in the exhaust gas outside said gap; and a control circuit coupled to said sensor, including an input portion (A) for comparing a predetermined reference voltage (V) with the said electromotive force to continuously provide an output until the said electromotive force reaches the reference voltage, and an output portion (Tr) for driving a pump current through said oxygen pump cell (3) in response to the output of said input portion whereby the air/fuel ratio of the engine is detected according to an output corresponding to the pump current, characterised in that the input portion (A) has a transfer function of an amplifier component (R2) plus an integrator component (C).
Claim 3
Dependent Claim
103 words
An engine air/fuel ratio sensing device as claimed in claim 1 wherein said input portion comprises an input resistor (Rl) one end of which is conncted to one of the electrodes of said sensor cell (4), a differential amplifier (A) the inverting input of which is connected to the other end of said input resistor and the non-inverting input of which is connected to a source of said predetermined reference voltage,and a feedback circuit conncted between the inverting input and the output of said differential amplifier, characterised in that the feedback circuit consists of a feedback resistor (R2) and a feedback capacitor (C).
Claim 4
Dependent Claim
47 words
An engine air/fuel ratio sensing device as claimed in claim 2 characterised in that said tansfer function is given by R2/Rl+l/sCR1. where R2 represents the resistance of said feedback resistor, Rl the resistance of said input resistor, s Laplacian, and C the capacitance of said feedback capacitor.
Claim 5
Dependent Claim
90 words
An engine air/fuel ratio sensing devices claimed in claim 2 or 3 characterised in that said output portion comprises a transistor (Tr) whose base is connected to the output of said differential amplifier (A) and whose collector is grounded through a DC power source (B), and a current limiting resistor (Ro) connected between the emitter of said transistor and one of the electrodes of said pump cell (3), the voltage drop of said current limiting resistor being used as an output of said control circuit means for a fuel control.
Claim 6
Dependent Claim
38 words
An engine air/fuel ratio sensing device as claimed in any preceding claim characterised by a base for supporting said pump cell and said sensor cell so that both cells project into an exhaust pipe having said gap portion.
Claim 7
Dependent Claim
21 words
An engine air/fuel ratio sensing device as claimed in any preceding claim characterised in that said solid electrolyte comprises stabilized zirconia.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.