Ngk Spark Plug Company, Limited

Keigo Banno

Noboru Ishida

Yoshikuni Sato

Hideki Ishikawa

Takafumi Oshima

Masashi Sakamoto

Norikazu Ieda

Yoshinori Inoue

Hiroshi Inagaki

Masahiro Tanaka

Takeshi Morita

Tatsuki Hirabayashi

Reina Kito

Katsuya Otake

A gas sensor apparatusin an air-fuel ratio detection systemincludes a gas sensor elementwhich outputs a detection signal corresponding to air-fuel ratio, and a gas sensor control circuitwhich includes a detection sectionfor outputting a first output signal VIP, a second output signal VIP, and a third output signal VIPin accordance with the detection signal. This detection sectionoutputs the first output signal VIPwhich changes in accordance with the air-fuel ratio at least within a wide first air-fuel ratio zone, the second output signal VIPwhich changes in accordance with the air-fuel ratio within a narrow zone in the vicinity of the stoichiometric ratio, and the third output signal VIPwhich changes in accordance with the air-fuel ratio within a narrow zone in the lean region.

Sensor control device and air fuel ratio detecting apparatus

An abnormality diagnosis method for a gas concentration measuring device, includes electrically shutting off measurement means from an oxygen concentration detecting cell and an oxygen pump cell of a gas sensor when a voltage at one of electrical connection points through which the measurement means is electrically connected to the oxygen concentration detecting cell and the oxygen pump cell becomes equal to a predetermined abnormal voltage value, and thereafter, electrically connecting the measurement means to the oxygen concentration detecting cell and the oxygen pump cell of the gas sensor to perform an abnormality diagnosis of the gas sensor. An abnormality diagnosis apparatus for a gas concentration measuring device is also provided.

Abnormality diagnosis method and apparatus for gas concentration measuring device

A gas sensor () including a measurement chamber () into which a gas GS is flown and a detection element main body () facing the measurement chamber (). The detection element main body () includes an element caseand a protective film () is adhered to a bottom surface thereof. An acoustic matching plate () and a piezoelectric element () of a substantially columnar shape and a tube body () provided in a position surrounding the acoustic matching plateand the piezoelectric elementare housed in the element case (). A filler is then introduced into the element case (), whereby the acoustic matching plate (), the piezoelectric element (), and the tube body () are sealed by a filled layer ().

Gas sensor

A detecting-element assembly () is configured such that a piezoelectric element () is housed in a casing body portion () of a casing (), and is attached to a housing portion () of a flow path formation member () via a flange portion (). Therefore, the path between the piezoelectric element () and the position of attachment of the detecting-element assembly () is elongated, whereby ultrasonic waves which leak into the interior of the detecting-element assembly () from the piezoelectric element () become unlikely to reflectively return from a joint. Thus, the influence of, for example, noise stemming from reflected waves is reduced, thereby enhancing the accuracy of detection. An average clearance of 1 millimeter or more is provided along the outer circumferential surface of the casing body portion () of the detecting-element assembly (), whereby a problem of collected foreign matter is unlikely to occur.

Sensor and method for manufacturing the same

A gas concentration sensor includes a measurement chamber for measuring a concentration of a specific gas component in a gas under measurement; an inflow path for allowing inflow of the gas under measurement thereinto and an outflow path for allowing outflow of the gas under measurement therefrom; a reflection wall for reflecting an acoustic wave; and an acoustic wave transmitting-receiving element having a transmitting-receiving surface adapted to transmit an acoustic wave toward the reflection wall and receive an acoustic wave reflected from the reflection wall. The concentration of the specific gas in the gas under measurement is detected on the basis of a propagation time between transmission of the acoustic wave and reception of the reflected acoustic wave. When a predetermined member having the sensor attached thereto is placed in a horizontal plane, the transmitting-receiving surface faces downward. A recess is formed in a peripheral portion of the reflection wall. The recess is receded toward a back surface of the reflection wall, namely, in a direction away from the transmitting-receiving surface.

Gas concentration sensor

An ultrasonic-wave propagation-time measuring method and gas concentration sensor are disclosed in which a reception wave which has been transmitted and received by an ultrasonic elementis subjected to full-wave rectification in order to obtain a full-wave-rectified wave, which is then integrated by an integration circuitto obtain an integral value. A peak value of the integral value is held by a peak-hold circuit. As to detection of gas concentration, a threshold-level calculation sectionsets a reference value on the basis of the peak value, and a point in time when the amplitude of a reception wave having undergone full-wave rectification is judged by a comparatorto have reached the reference value is regarded as an arrival time. Subsequently, a gas concentration is determined on the basis of a period between the emission time and the arrival time.

Ultrasonic-wave propagation-time measuring method and gas concentration sensor

An ultrasonic-wave propagation time measuring method which enables determination of accurate propagation time, a gas-pressure measuring method, a gas-flow-rate measuring method, and a gas sensor. A reception wave which has been transmitted and received by an ultrasonic element is shaped and integrated by an integration circuit to obtain an integral value. A peak value of the integral value is held by a peak-hold circuit . As to detection of gas concentration, a resistance-voltage-division circuit sets a reference value on the basis of the peak value, and a point in time when the integral value of the reception wave is judged by a comparator to have reached the reference value is regarded as an arrival time. Subsequently, a gas concentration is detected on the basis of a period between the emission time and the arrival time. As to detection of gas pressure and flow rate, the gas pressure is detected on the basis of the peak value, and further, the gas flow rate is calculated on the basis of the gas pressure.

Ultrasonic-wave propagation-time measuring method, gas-pressure measuring method, gas-flow rate measuring method, and gas sensor

A gas concentration sensor comprises an ultrasonic element,opposite a reflection surface,A depression,is formed on an edge portion of a reflection surface,which is in contact with a side wall of a measurement chamber,such that a bottom surface of the depression,is substantially in parallel with the reflection surface,The distance between the ultrasonic element,and the edge portion of the reflection surface,becomes greater than the distance between the ultrasonic element,and a central portion of the reflection surface,As a result, an indirect wave, which impinges obliquely on the side wall of the measurement chamber,and propagates along the side wall, is reflected from the bottom surface of the depression,and propagates. Thus, the propagation distance of this indirect wave becomes greater as compared to the case where the reflection surface,is flat, so that the indirect wave is not combined with a direct wave in the vicinity of a modulation point of the direct wave. That is, since the modulation point of the direct wave can be detected accurately, a time interval between a modulation point of a transmitted wave and that of a received wave can be measured as the propagation time of an ultrasonic wave, thereby enabling accurate determination of gas concentration.

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Aichi, Japan

Keigo Banno