Ngk Spark Plug Company, Limited

Mitsubishi Denki Kabushiki Kaisha

Mitsubishi Denki K.k.

Kabushiki Kaisha

Mitsubishi Denki Ngk Spark Plug Co. Ltd.

Shintaro Hirate

Tetsusyo Yamada

Yoshiaki Asayama

An air/fuel ratio detector comprising a pump and an electrochemical cell in which both the pump and electrochemical cell comprise an oxygen ion conductive solid electrolyte sandwiched between porous electrodes. One of the elements has an insulating substrate formed on a portion of the electrolyte. Over the substrate is formed a layer of semiconducting metal oxide. The cell and pump face each other with the cell providing an EMF and the pump being pumped by a pump current. The size of the resistance of the metal oxide layer indicates whether the air/fuel mixture is rich or lean relative to a stoichiometric mixture and the values of the EMF and pump current indicate the deviation from stoichiometry.

Air/fuel ratio detector

An air/fuel ratio detector providing an unambiguous output for both fuel-rich and fuel-lean regions is disclosed. The detector includes a solid-electrolyte oxygen-concentration-difference-actuated electrochemical cell sensor element and a solid-electrolyte oxygen pump element, each element being in the form of an oxygen-ion-conductive solid electrolyte having a porous electrode formed on both sides thereof. The electrochemical cell sensor element is disposed to face the pump element with a small gap therebetween. An air compartment open to the atmosphere is formed on the side of the pump element opposite the small gap. One terminal of the pump element is connected to a switch having at least two positions, one providing connection to a varying current source for maintaining the electromotive source of the electrochemical cell sensor at a predetermined value, and another position providing connection to a constant current source for maintaining the pump current flowing through the pump element at a fixed predetermined level. The air/fuel ratio is detected by an output signal provided by one of the electromotive force of the sensor element and the pump current.

An air/fuel ratio detector for use in measuring or controlling oxygen concentration in exhaust gas from a combustion device, comprising a plurality of solid electrolyte, oxygen ion conducting elements and an electronic control unit. The detector output, which is different over a wide range of air/fuel ratios, from fuel-rich to fuel-lean, enables monitoring of engine operating conditions without having to know beforehand whether the air/fuel ratio is fuel-lean or fuel-rich, and may be used as a feedback control in an internal combustion engine.

An A/F (Air Fuel) ratio detector providing precise control of the operating A/F ratio of an internal combustion engine whether the engine is operating in the fuel-rich or fuel-lean region or at the theoretical (stoichiometric) point. The detector includes both a pump element and a sensor element, each composed of an oxygen-ion-conductive solid electrolyte having formed on both sides thereof a porous electrode. The pump and sensor elements are disposed facing one another with a small gap therebetween. A wall is disposed parallel to the sensor element on the side opposite the gap and is sealed to the solid electrolyte of the sensor element except at a base portion, thereby defining an air compartment open to the atmosphere. An electric current is passed through the pump element, and the resulting potential produced across the sensor element is taken as an indication of the operating A/F ratio.

An A/F ratio detector capable of accurately and unambiguously detecting the operating A/F ratio of a burner such as an internal combustion engine whether the engine is operating in the fuel-rich region, fuel-lean region or at the theoretical A/F ratio. The detector includes a solid-electrolyte oxygen pump element having a porous electrode formed on both sides of an oxygen-ion-conductive solid electrolyte, and a solid-electrolyte oxygen-concentration-difference-actuated electrochemical cell sensor element disposed to face the pump element with a small gap therebetween and which has two porous electrodes formed on opposite sides of an oxygen-ion-conductive solid electrolyte. An air compartment open to the atmosphere is formed on a side of the electrochemical cell sensor element opposite the small gap. The electromotive force generated by one pair of the porous electrodes on the electrochemical cell sensor element, the pump current flowing through the other pair of porous electrodes on the sensor element, or the pump current flowing through the porous electrodes on the pump element provides an output signal for A/F ratio detection.

An air/fuel ratio detector capable of producing an unambiguous output for both fuel-rich and fuel-lean regions. A solid-electrolyte oxygen-concentration-difference-actuated electrochemical cell sensor element is provided having a porous electrode formed on both sides of an oxygen-ion-conductive solid electrolyte. A solid-electrolyte oxygen pump element is also provided with a porous electrode formed on both sides of an oxygen-ion-conductive solid electrolyte. An oxygen reference element has a metal oxide semiconductor layer formed on one side of a substrate made of an air-impermeable member. The electrochemical cell sensor element and the pump element are disposed facing one another with a small gap therebetween. An air compartment open to the atmosphere is formed between that side of the pump element opposite the side facing the small gap and the side of the reference element opposite the side having the metal oxide semiconductor layer. The air/fuel ratio is detected both by a change in the electrical properties of the oxygen reference element and by output signal provided by at least one of the electromotive force of the electrochemical cell sensor element and a pump current flowing through the pump element.

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Aichi, Japan

Shintaro Hirate